Arthur C Clarke - The City and the Stars Preface For the benefit of tho who have read my first novel, against the fall of night, and will recognize some of the material in the present work, a few words of explanation are in order. Against the fall of night was begun in 1937 and, after four or five drafts, was completed in 1946, though for various reasons beyond the author's control book publication was delayed until some years later. Although this
work was well received, it had most of the defects of a first novel, and m initial dissatisfaction with it increased steadily over the years. Moreover,
the progress of science during the two decades since the story was first conceived made many of the original ideas naive, and opened up vistas and possibilities quite unimagined when the book was originally planned. In particular, certain developments in information theory suggested revolutions
in the human way of life even more profound than those which atomic energy already introducing, and i wished to incorporate these into the book i had attempted, but so far failed, to write. A sea voyage from England to Austral gave an opportunity of getting to grips with the uncompleted job, which was finished just before i set out to the great barrier reef. The knowledge that was to spend some months diving among sharks of doubtful docility was an additional spur to action. It may or may not be true, as doctor Johnson stated, that nothing settles a man's mind so much as the knowledge that he will be hanged in the morning, but for my part i can testify that the thou of not returning from the reef was the main reason why the book was complet at that particular time, and the ghost that had haunted me for almost twenty years was finally exorcised. About a quarter of the present work appeared in against the fall of night; it is my belief, however, that even those who re the earlier book will find that this is virtually a new novel. If not, at least i hope they will grant an author the right to have second thoughts. I promise them that this is my last word on the immortal city of Diaspora, in the long twilight of earth. Arthur c. Clarke London, September, 1954 - S.D. Himalayan - Sydney, march, 1955 Like a glowing jewel, the city lay upon th breast of the desert. Once it had known change and alteration, but now time passed it by. Night and day fled across the desert's face, but in the stree of Diaspora it was always afternoon, and darkness never came. The long winter nights might dust the desert with frost, as the last moisture left in the t air of earth congealed-but the city knew neither heat nor cold. It had no contact with the outer world; it was a universe itself. Men had built cities before, but never a city such as this. Some had lasted for centuries, some millenniums, before time had swept away even their names. Diaspora alone had challenged eternity, defending itself and all it sheltered against the slow attrition of the ages, the ravages of decay, and the corruption of rust. Sin the city was built, the oceans of earth had passed away and the desert had encompassed all the globe. The last mountains had been ground to dust by the winds and the rain, and the world was too weary to bring forth more. The c did not care; earth itself could crumble and Diaspora would still protect the children of its makers, bearing them and their treasures safely down the
stream of time. They had forgotten much, but they did not know it. They wer as perfectly fitted to their environment as it was to them -for both had be designed together. What was beyond the walls of the city was no concern of theirs; it was something that had been shut out of their minds. Diaspora was all that existed, all that they needed, all that they could imagine. It mattered nothing to them that man had once possessed the stars. Yet sometimes the ancient myths rose up to haunt them, and they stirred uneasily as they remembered the legends of the empire, when Diaspora was young and drew its lifeblood from the commerce of many suns. They did not wish to bring back t old days, for they were content in their eternal autumn. The glories of the empire belonged to the past, and could remain there-for they remembered how
the empire had met its end, and at the thought of the invaders the chill o space itself came seeping into their bones. Then they would turn once more t the life and warmth of the city, to the long golden age whose beginning was

years had worn away. One It had taken them of the cave of the white worms. Even now, they the pallid monsters were not pursuing them -and
their wa that some weapons w
almost exhausted. Ahead, the floating arrow of light that had been their mysterious guide through the labyrinths of the crystal mountain still beckoned them on. They had no choice but to follow it, though as it had done so ma times before it might lead them into yet more frightful dangers. Alvin glance back to see if all his companions were still with him. Alystra was close behind, carrying the sphere of cold but ever-burning light that had revealed such horrors and such beauty since their adventure had begun. The pale white radiance flooded the narrow corridor and splashed from the glittering walls; while its power lasted, they could see where they were going and could detec the presence of any visible dangers. But the greatest dangers in these caves, Alvin knew too well, were not the visible ones at all. Behind Alystra, struggling with the weight of their projectors, came brilliant and lorans.
Alvin wondered briefly why those projectors were so heavy, since it would hav been such a simple matter to provide them with gravity neutralizers. He was always thinking of points like this, even in the midst of the most desperate adventures. When such thoughts crossed his mind, it seemed as if the structur of reality trembled for an instant, and that behind the world of the senses caught a glimpse of another and totally different universe.... The corridor ended in a blank wall. Had the arrow betrayed them again? No-even as they approached, the rock began to crumble into dust. Through the wall pierced a spinning metal spear, which broadened rapidly into a giant screw. Alvin and
his friends moved back, waiting for the machine to force its way into the cave. With a deafening screech of metal upon rock-which surely must echo through all the recesses of the mountain, and waken all its nightmare
brood!-the sub terrene smashed through the wall and came to rest beside them. A massive door opened, and callistron appeared, shouting to them to hurry. ("Why callistron?" wondered Alvin. "What's he doing here?") a moment later
they were in safety, and the machine lurched forward as it began its journey through the depths of the earth. The adventure was over. Soon, as always happened, they would be home, and all the wonder, the terror, and the excitement would be behind them. They were tired and content. Alvin could tel from the tilt of the floor that the sub terrene was heading down into the earth. Presumably callistron knew what he was doing, and this was the way th led to home. Yet it seemed a pity... "Callistron," he said suddenly, "why don't we go upward? No one knows what the crystal mountain really looks like How wonderful it would be to come out somewhere on its slopes, to see the and all the land around it. We've been underground long enough." even as he said these words, he somehow knew that they were wrong. Alystra gave a strangled scream, the interior of the sub terrene wavered like an image seen through water, and behind and beyond the metal walls that surrounded him Alvi once more glimpsed that other universe. The two worlds seemed in conflict, first one and then the other predominating. Then quite suddenly, it was all over. There was a snapping, rending sensation-and the dream had ended. Alvin was back in Diaspora, in his own familiar room, floating a foot or two abov the floor as the gravity field protected him from the bruising contact of brute matter. He was himself again. This was reality-and he knew exactly wh would happen next. Alystra was the first to appear. She was more upset than annoyed, for she was very much in love with Alvin. "Oh, Alvin!" she lamented as she looked down at him from the wall in which she had apparently materialized, "it was such an exciting adventure! Why did you have to spoil it?" "I'm sorry. I didn't intend to -- I just thought it would be a good idea..." He was interrupted by the simultaneous arrival of callistron and floranus. "Now listen, Alvin," began callistron. "This is the third time
you've interrupted a saga. You broke the sequence yesterday by wanting to

climb out of the valley of rainbows. And the day before you upset everything by trying to get back to the origin in that time track we were exploring. you won't keep the rules, you'll have to go by yourself." he vanished in hi dudgeon taking floranus with him. Narillian never appeared at all; he was probably too fed up with the whole affair. Only the image of alystra was le looking sadly down at alvin. Alvin tilted the gravity field, rose to his fee and walked toward the table he had materialized. A bowl of exotic fruit appeared upon it-not the food he had intended, for in his confusion his thoughts had wandered: not wishing to revealhis error, he picked up the least dangerous-looking of the fruits and started to suck it cautiously. "Well,"
said alystra at last, "what are you going to do?" "i can't help it," he sa little sulkily. "I think the rules are stupid. Besides, how can i remember them when i'm living a saga? I just behave in the way that seems natural. Didn't you want to look at the mountain?" alystra's eyes widened with horror. "That would have meant going outside!" she gasped. Alvin knew that it was useless to argue further. Here was the barrier that sundered him from all th people of his world, and which might doom him to a life of frustration. He always wanting to go outside, both in reality and in dream. Yet to everyone diaspar, "outside" was a nightmare that they could not face. They would never talk about it if it could be avoided; it was something unclean and evil. No even jeserac his tutor, would tell him why. Alystra was still watching him with puzzled but tender eyes. "You're unhappy, alvin," she said. ` No one should be unhappy in diaspar. Let me come over and talk to you." ungallantly alvin shook his head. He knew where that would lead and at the moment he wanted to be alone. Doubly disappointed, alystra faded from view. In a city ten million human beings, thought alvin, there was no one to whom he could really talk. Eriston and etania were fond of him in their way, but now that their term of guardianship was ending, they were happy enough to leave him t shape his own amusements and his own life. In the last few years, as his divergence from the standard pattern became more and more obvious, he had
often felt his parents' resentment. Not with him-that perhaps, was something he could have faced and fought-but with the sheer bad luck that had chosen them from all the city's millions, to meet him when he walked out of the h of creation twenty years ago. Twenty years. He could remember the first
moment, and the first words he had ever heard: "welcome, alvin. I am eriston your appointed father. This is etania, your mother." the words had meant nothing then, but his mind had recorded them with flawless accuracy. He remembered how he had looked down at his body; it was an inch or two talle now, but had scarcely altered since the moment of his birth. He had come almost fully grown into the world, and would have changed little save in height when it was time to leave it a thousand years hence. Before that fir memory, there was nothing. One day, perhaps, that nothingness would come
again, but that was a thought too remote to touch his emotions in any way. turned his mind once more toward the mystery of his birth. It did not seem strange to alvin that he might be created, in a single moment of time, by powers and forces that materialized all the other objects of his everyday life. No; that was not the mystery. The enigma he had never been able to
solve, and which no one would ever explain to him, was his uniqueness. Uniqu It was a strange, sad word-and a strange, sad thing to be. When it was app to him-as he had often heard it done when no one thought he was listening-i seemed to possess ominous undertones that threatened more than his own happiness. His parents, his tutor, everyone he knew, had tried to protect him from the truth, as if anxious to preserve the innocence of his long childhoo The pretense must soon be ended; in a few days he would be a full citizen diaspar, and nothing could be withheld from him that he wished to know. Why, for example, did he not fit into the sagas? Of all the thousands of forms recreation in the city, these were the most popular. When you entered a saga you were not merely a passive observer, as in the crude entertainments of primitive times which alvin had sometimes sampled. You were an active participant and possessed-or seemed to possess-free will. The events and

scenes which were the raw material of your adventures might have been prepare beforehand by forgotten artists, but there was enough flexibility to allow for wide variation. You could go into these phantom worlds with your friends, seeking the excitement that did not exist in diaspar-and as long as the drea lasted there was no way in which it could be distinguished from reality. Indeed, who could be certain that diaspar itself was not the dream? No one could ever exhaust all the sagas that had been conceived and recorded since the city began. They played upon all the emotions and were of infinitely varying subtlety. Some-those popular among the very young-were uncomplicated dramas of adventure and discovery. Others were purely explorations of psychological states, while others again were exercises in logic or
mathematics which could provide the keenest of delights to more sophisticated minds. Yet though the sagas seemed to satisfy his companions, they left alvin with a feeling of incompleteness. For all their color and excitement, their varying locales and themes, there was something missing. The sagas, he
decided, never really got anywhere. They were always painted on such a narrow canvas. There were no great vistas, none of the rolling landscapes for which his soul craved. Above all, there was never a hint of the immensity in whic the exploits of ancient man had really taken place -the luminous void between the stars and planets. The artists who had planned the sagas had been infect by the same strange phobia that ruled all the citizens of diaspar. Even thei vicarious adventures must take place cozily indoors, in subterranean caverns,
or in neat little valleys surrounded by mountains that shut out all the rest of the world. There was only one explanation. Far back in time, perhaps befo diaspar was founded, something had happened that had not only destroyed man's curiosity and ambition, but had sent him homeward from the stars to cower fo shelter in the tiny closed world of earth's last city. He had renounced the universe and returned to the artificial womb of diaspar. The flaming,
invincible urge that had once driven him over the galaxy, and to the islands of mist beyond, had altogether died. No ships had entered the solar system f countless aeons; out there among the stars the descendants of man might still be building empires and wrecking suns-earth neither knew nor cared. Earth did not. But alvin did. Two The room was dark save for one glowing wall, up which the tides of color ebbed and flowed as alvin wrestled with his dreams. Part of the pattern satisfied him; he had fallen in love with the soaring lines of the mountains as they leaped out of the sea. There was a power an pride about those ascending curves; he had studied them for a long time, and then fed them into the memory unit of the visualizes, where they would be preserved while he experimented with the rest of the picture. Yet something
was eluding him, though what it was he did not know. Again and again he ha tried to fill in the blank spaces, while the instrument read the shifting patterns in his mind and materialized them upon the wall. It was no good. T lines were blurred and uncertain, the colors muddy and dull. If the artist d not know his goal, even the most miraculous of tools could not find it for him. Alvin canceled his unsatisfactory scribblings and stared morosely at the three-quarters-empty rectangle he had been trying to fill with beauty. On a sudden impulse, he doubled the size of the existing design and shifted it to the center of the frame. No-that was a lazy way out, and the balance was a wrong. Worse still, the change of scale had revealed the defects in his construction, the lack of certainty in those atfirst-sight confident lines. He would have to start all over again. "Total erasure," he ordered the machine. The blue of the sea faded; the mountains dissolved like mist, until only the blank wall remained. They were as if they had never beenas if they were los in the limbo that had taken all earth's seas and mountains ages before alvin was born. The light came flooding back into the room and the luminous rectangle upon which alvin had projected his dreams merged into its surroundings, to become one with the other walls. But were they walls? To anyone who had never seen such a place before, this was a very peculiar roo indeed. It was utterly featureless and completely devoid of furniture, so that it seemed as if alvin stood at the center of a sphere. No visible dividing

lines separated walls from floor or ceiling. There was nothing on which the eye could focus; the space enclosing alvin might have been ten feet or ten miles across, for all that the sense of vision could have told. It would ha been hard to resist the temptation to walk forward, hands outstretched, to discover the physical limits of this extraordinary place. Yet such rooms had been "home" to most of the human race for the greater part of its history. Alvin had only to frame the appropriate thought, and the walls would become windows opening upon any part of the city he chose. Another wish, and machin which he had never seen would fill the chamber with the projected images of any articles of furniture he might need. Whether they were "real" or not was problem that had bothered few men for the last billion years. Certainly they were no less real than that other impostor, solid matter, and when they were no longer required they could be returned to the phantom world of the city's memory banks. Like everything else in diaspar, they would never wear out-and they would never change, unless their stored patterns were canceled by a deliberate act of will. Alvin had partly reconstructed his room when a persistent, bell-like chime sounded in his ear. He mentally framed the
admission signal, and the wall upon which he had just been painting dissolved once more. As he bad expected, there stood his parents, with jeserac a littl behind them. The presence of his tutor meant that this was no ordinary famil reunion -but he knew that already.... The illusion was perfect, and it was n lost when eriston spoke. In reality, as alvin was well aware, eriston etania, and jeserac were all miles apart, for the builders of the city had conquered space as completely as they had subjugated time. Alvin was not even certain where his parents lived. Among the multitudinous spires and intricate
labyrinths of diaspar, for they had both moved since he had last been physically in their presence. Alvin," began eriston, "it is just twenty year since your mother and i first met you. You know what that means. Our guardianship is now ended, and you are free to do as you please." there was trace--but merely a trace--of sadness in brixton's voice. There was
considerably more relief, as if eriston was glad that a state of affairs tha had existed for some time in fact now had legal recognition. Alvin had anticipated his freedom by a good many years. "I understand," he answered. "I thank you for watching over me, and i will remember you in all my lives." was the formal response; he had heard it so often that all meaning had been leached away from it-it was merely a pattern of sounds with no particular significance. Yet "all my lives" was a strange expression, when one stopped t consider it. He knew vaguely what it meant; now the time had come for him know exactly. There were many things in diaspar which he did not understand, and which he would have to learn in the centuries that lay ahead of him. F moment it seemed as if etania wished to speak. She raised one hand, disturbi the iridescent gossamer of her gown, then let it fall back to her side. The she turned helplessly to jeserac, and for the first time alvin realized that his parents were worried. His memory swiftly scanned the events of the past few weeks. No, there was nothing in his recent life that could have caused this faint uncertainty, this air of mild alarm that seemed to surround both eriston and etania. Jeserac, however, appeared to be in command of the situation. He gave an inquiring look at eriston and etania, satisfied himself that they had nothing more to say, and launched forth on the dissertation he had waited many years to make. "Alvin," he began, "for twenty years you have been my pupil, and i have done my best to teach you the ways of the city, to lead you to the heritage which is yours. You have asked me many question and not all of them have i been able to answer. Some things you were not
to learn, and some i did not know myself. Now your infancy is over, though your childhood is scarcely begun. It is still my duty to guide you, if you need my help. In two hundred years, alvin , you may begin to know something this city and a little of its history. Even i, who am nearing the end of life, have seen less than a quarter of diaspar, and perhaps less than a thousandth of its treasures." there was nothing so far that alvin did not know, but there was no way of hurrying jeserac. The old man looked steadfast

words weighed down with the lifetime's contact with men and
machines. "Tell me, alvin," he said, "have you ever asked yourself where you were before you were born-before you found yourself facing etania and eriston at the hall of creation?" "i assumed i was nowhere-that i was nothing but a pattern in the mind of the city, waiting to be created-like this." a low co glimmered and thickened into reality beside alvin. He sat down upon it and waited for jeserac to continue. "You are correct, of course," came the repl "But that is merely part of the answer-and a very small part indeed. Until now, you have met only children of your own age, and they have been ignoran of the truth. Soon they will remember, but you will not, so we must prepare you to face the facts. For over a billion years, alvin, the human race has lived in this city. Since the galactic empire fell, and the invaders. Went back to the stars, this has been our world. Outside the walls of diaspar, there is nothing except the desert of which our legends speak. "We know litt about our primitive ancestors, except that they were very short-lived beings
and that, strange though it seems, they could reproduce themselves without the aid of memory units or matter organizers. In a complex and apparently uncontrollable process, the key patterns of each human being were preserved in microscopic cell structures actually created inside the body. If you are interested, the biologists can tell you more about it, but the method is of great importance since it was abandoned at the dawn of history. "A human being, like any other object, is defined by its structure-its pattern. The pattern of a man, and still more the pattern which specifies a man's mind, incredibly complex. Yet nature was able to pack that pattern into a tiny cel too small for the eye to see. "What nature can do, man can do also, in hi way." we do not know how long the task took. A million years, perhaps-but w is that? In the end our ancestors learned how to analyze and store the information that would define any specific human being-and to use that information to re-create the original, as you have just created that couch. " know that such things interest you, alvin, but i cannot tell you exactly how it is done. The way in which information is stored is of no importance; all that matters is the information itself. It may be in the form of written wo on paper, n of varying magnetic fields, or patterns of electric charge. Men have used all these methods of storage, and many others. Suffice to say that long ago they were able to store themselvesor, to be more precise, the disembodied patterns from which they could be called back into existence. "So much, you already know. This is the way our ancestors gave us virtual immortality, yet avoided the problems raised by the abolition of death. A thousand years in one body is long enough for any man; at the end of that time, his mind is clogged with memories, and he asks only for rest-or a new beginning. In a little while, alvin, i shall prepare to leave this life. I shall go back through my memories, editing them and canceling those i do not wish to keep. Then i shall walk into the hall of creation, but through a d which you have never seen. This old body will cease to exist, and so will consciousness itself. Nothing will be left of jeserac but a galaxy of
electrons frozen in the heart of a crystal. "I shall sleep, alvin, and witho dreams. Then one day, perhaps a hundred thousand years from now, i shall fin myself in a new body, meeting those who have been chosen to be my guardians They will look after me as eriston and etania have guided you, for at first will know nothing of diaspar and will have no memories of what i was before Those memories will slowly return, at the end of my infancy, and i will bui upon them as i move forward into my new cycle of existence. "That is the pattern of our lives, alvin. We have all been here many, many times before, though as the intervals of nonexistence vary according to apparently random
laws this present population will never repeat itself again. The new jeserac will have new and different friends and interests, but the old jeserac-as muc of him as i wish to save-will still exist. "That is not all. At any moment alvin, only a hundredth of the citizens of diaspar live and walk its streets The vast majority slumber in the memory banks, waiting for the signal that

will call them forth onto the stage of existence once again. So we have continuity, yet change-immortality, but not stagnation. I know what you are wondering, alvin. You want to know when you will recall the memories of your earlier lives, as your companions are already doing. "There are no such memories, for you are unique. We have tried to keep this knowledge from you long as we could, so that no shadow should lie across your childhood-though think you must have guessed part of the truth already. We did not suspect i ourselves until five years ago, but now there is no doubt. "You alvin, are something that has happened in diaspar a handful of times since the founding of the city. Periys you have been lying dormant in the memory banks through all the ages-or perhaps you were created only twenty years ago by some rando permutation. You may have been planned in the beginning by the designers of the city, or you may be a purposeless accident of our own time. "We do not know. All that we do know is this: you, alvin, alone of the human race, ha never lived before. In literal truth, you are the first child to be born on earth for at least ten million years." Three When jeserac and his parents had faded from view, alvin lay for a long time trying to hold his mind emp of thought. He closed his room around him, so that no one could interrupt h trance. He was not sleeping; sleep was something he had never experienced, for that, belonged to a world of night and day, and here there was only da This was the nearest he could come to that forgotten state, and though it w not really essential to him he knew that it would help compose his mind.
had learned little new; almost everything that jeserac had told him he had already guessed. But it was one thing to have guessed it, another to have h that guess confirmed beyond possibility of refutation. How would it affect
his life, if at all? He could not be sure, and uncertainty was a novel sensation to alvin. Perhaps it would make no difference whatsoever; if he did not adjust completely to diaspar in this life, he would do so in the next the next. Even as he framed the thought, alvin's mind rejected it. Diaspar might be sufficient for the rest of humanity, but it was not enough for him He did not doubt that one could spend a thousand lifetimes without exhausting all its wonders, or sampling all the permutations of experience it could provide. These things he could do-but if he could not do more, he would nev be content. There was only one problem to be faced. What more was there t do? The unanswered question jolted him out of his reverie. He could not st here while he was in this restless mood, and there was only one place in t city where he could find some peace of mind. The wall flickered partially
of existence as he stepped through to the corridor, and its polarized molecules resisted his passage like a feeble wind blowing against his face. There were, many ways in which he could be carried effortlessly to his goal, but he preferred to walk. His room was almost at the main city level, and short passage brought him out onto a spiral ramp which led down to the stre He ignored the moving way, and kept to the narrow sidewalk-an eccentric thing to do, since he had several miles to travel. But alvin liked the exercise,
it soothed his mind. Besides, there was so much to see that it seemed a pi to race past the latest marvels of diaspar when you had eternity ahead of y It was the custom of the city's artists-and everyone in diaspar was an artis at some time or another-to display their current productions along the side o the moving ways, so that the passers-by could admire their work. In this manner, it was usually only a few days before the entire population had critically examined any noteworthy creation, and also expressed its views upon it. The resulting verdict, recorded automatically by opinion-sampling devices which no one had ever been able to suborn or deceive and there had been en attempts-decided the fate of the masterpiece. If there was a sufficiently affirmative vote, its matrix would go into the memory of the city so that anyone who wished, at any future date, could possess a reproduction utterly indistinguishable from the original. The less successful pieces went the way
of all such works. They were either dissolved back into their original elements or ended in the homes of the artists' friends. Alvin saw only one object d'art on his journey that had any appeal to him. It was a creation

pure light, vaguely reminiscent of an unfolding flower. Slowly growing from a minute core of color, it would expand into complex spirals and curtains, then suddenly collapse and begin the cycle over again. Yet not precisely, for no two cycles were identical. Though alvin watched through a score of pulsations, each time there were subtle and indefinable differences, even though the basic pattern remained the same. He knew why he liked this piece of intangible sculpture. Its expanding rhythm gave an impression of space -even of escape. For that reason, it would probably not appeal to many of alvin's compatriots. He made a note of the artist's name and decided to call him at the earlies opportunity. All the roads both moving and stationary, came to an end when they reached the park that was the green heart of the city. Here, in a circular space over three miles across, was a memory of what earth had been the days before the desert swallowed all but diaspar. First there was a wide belt of grass, then low trees which grew thicker and thicker as one walked forward beneath their shade. At the same time the ground sloped gently
downward so that when at last one emerged from the narrow forest all sign o the city had vanished, hidden by the screen of trees. The wide stream that ahead of alvin was called, simply, the river. It possessed, and it needed, n other name. At intervals it was spanned by narrow bridges, and it flowed around the park in a complete, closed circle, broken by occasional lagoons. That a swiftly moving river could return upon itself after a course of less than six miles had never struck alvin as at all unusual; indeed, he would n have thought twice about the matter if at some point in its circuit the riv had flowed uphill. There were far stranger things than this in diaspar. A dozen young people were swimming in one of the little lagoons, and alvin paused to watch them. He knew most of them by sight, if not by name, and moment was tempted to join in their play. Then the secret he was bearing decided him against it, and he contented himself with the role of
spectator. Physically, there was no way of telling which of these young citizens had walked out of the hall of creation this year and which had liv in diaspar as long as alvin. Though there were considerable variations in height and weight, they had no correlation with age. People were simply born that way, and although on the average the taller the person, the greater the age, this was not a reliable rule to apply unless one was dealing in centuries. The face was a safer guide. Some of the newborn were taller tha alvin, but they had a look of immaturity, an expression of wondering surprise at the world in which they now found themselves that revealed them at once. was strange to think that, slumbering untapped in their minds, were infinite vistas of lives that they would soon remember. Alvin envied them, yet he was not sure if he should. One's first existence was a precious gift which would never be repeated. It was wonderful to view life for the very first time, a in the freshness of the dawn. If only there were others like him, with whom could share his thoughts and feelingst Yet physically he was cast in precisely the same mold as those children playing in the water. The human bo had changed not at all in the billion years since the building of diaspar, since the basic design had been eternally frozen in the memory banks of the city. It had changed, however, a good deal from its original primitive form, though most of the alterations were internal and not visible to the eye. Man had rebuilt himself many times in his long history, in the effort to abolish those ills to which the flesh was once heir. Such unnecessary appurtenances as nails and teeth had vanished. Hair was confined to the head; not a trace was left on the body. The feature that would most have surprised a man of dawn ages was, perhaps, the disappearance of the navel. Its inexplicable
absence would have given him much food for thought, and at first sight he would also have been baffled by the problem of distinguishing male from female. He might even have been tempted to assume that there was no longer difference, which would have been a grave error. In the appropriate
circumstances, there was no doubt about the masculinity of any male in iaspar It was merely that his equipment was now more neatly packaged when not required; internal stowage had vastly improved upon nature's original

inelegant and indeed downright hazardous arrangements. It was true that that reproduction was no longer the concern of the body, being far too important matter to be left to games of chance played with chromosomes as dice. Yet, though conception and birth were not even memories, sea remained. Even in ancient times, not one-hundredth part of sexual activity had been concerned
with reproduction. The disappearance of that mere one per cent had changed th pattern of human society and the meaning of such words as "father" and "mother"-but desire remained, though now its satisfaction had no profounder
aim than that of any of the other pleasures of the senses. Alvin left his playful contemporaries and continued on toward the center of the park. There were faintly marked paths here, crossing and crisscrossing through low shrubbery and occasionally diving into narrow ravines between great lichencovered boulders. Once he came across a small polyhedral machine, no
larger than a man's head, floating among the branches of a tree. No one kne how many varieties of robot there were in diaspar; they kept out of the way and minded their business so effectively that it was quite unusual to see
one. Presently the ground began to rise again; alvin was approaching the little hill that was at the exact center of the park, and therefore of the city itself. There were fewer obstacles and detours, and he had a clear view to the summit of the hill and the simple building that surmounted it. He wa little out of breath by the time he had reached his goal, and was glad to against one of the rose-pink columns and to look back over the way he had come. There are some forms of architecture that can never change because th have reached perfection. The tomb of yarlan zey might have been designed by the temple builders of the first civilizations man had ever known, though the would have found it impossible to imagine of what material it was made. The roof was open to the sky, and the single chamber was paved with great slabs which only at first sight resembled natural stone. For geological ages human feet had crossed and recrossed that floor and left no trace upon its inconceivably stubborn material. The creator of the great park-the builder, some said, of diaspar itself-sat with slightly downcast eyes, as if examining the plans spread across his knees. His face wore that curiously elusive expression that had baffled the world for so many generations. Some had dismissed it as no more than an idle whim of the artist's, but to others i seemed that yarlan zey was smiling at some secret jest. The whole building w an enigma, for nothing concerning it could be traced in the historical record of the city. Alvin was not even sure what the word "tomb" meant; jeserac co probably tell him, because he was fond of collecting obsolete words and sprinkling his conversation with them, to the confusion of his
listeners. From this central vantage point, alvin could look clear across th park, above the screening trees, and out to the city itself. The nearest buildings were almost two miles away, and formed a low belt completely surrounding the park. Beyond them, rank after rank in ascending height, were the towers and terraces that made up the main bulk of the city. They stretc for mile upon mile, slowly climbing up the sky, becoming ever more complex a monumentally impressive. Diaspar had been planned as an entity; it was a
single mighty machine. Yet though its outward appearance was almost overwhelming in its complexity, it merely hinted at the hidden marvels of technology, without which all these great buildings would be lifeless sepulchers. Alvin stared out toward the limits of his world. Twenty miles away, their details lost in distance, were the outer ramparts of the city, upon which seemed to rest the roof of the sky. There was nothing beyond
them-nothing at all except the aching emptiness of the desert in which a man would soon go mad. Then why did that emptiness call to him, as it called t one else whom he had ever met? Alvin did not know. He stared out across th colored spires and battlements that now enclosed the whole dominion of
mankind, as if seeking an answer to his question. He did nol find it. But that moment, as his heart yearned for the unattainable, he made his decision. He knew now what he was going to do with life. Four Jeserac was not ve helpful, though he was not as uncooperative as alvin had half expected. He h

been asked such questions before in his long career as mentor, and did not believe that even a unique like alvin could produce many surprises or set hi problems which he could not solve. It was true that alvin was beginning to show certain minor eccentricities of behavior, which might eventually need correction. He did not join as fully as he should in the incredibly elaborat social life of the city or in the fantasy worlds of his companions. He show no great interest in the higher realms of thought, though at his age that w hardly surprising. More remarkable was his erratic love life; he could not be expected to form any relatively stable partnerships for at least a century,
yet the brevity of his affairs was already famous. They were intense while they lasted-but not one of them had lasted for more than a few weeks. Alvin it seemed, could interest himself thoroughly only in one thing at a time. There were times when he would join wholeheartedly in the erotic games of hi companions, or disappear with the partner of his choice for several days. But once the mood had passed, there would be long spells when he seemed totally uninterested in what should have been a major occupation at his age. This wa probably bad for him, and it was certainly bad for his discarded lovers, who wandered despondently around the city and took an unusually long time to find consolation elsewhere. Alystra, jeserac had noticed, had now arrived at this unhappy stage. It was not that alvin was heartless or inconsiderate. In love, as in everything else, it seemed that he was searching for a goal that dias could not provide. None of these characteristics worried jeserac. A unique
might be expected to behave in such a manner, and in due course alvin would conform to the general pattern of the city. No single individual, however eccentric or brilliant, could affect the enormous inertia of a society that
had remained virtually unchanged for over a billion years. Jeserac did not merely believe in stability; he could conceive of nothing else. "The problem that worries you is a very old one," he told alvin, "but you will be surpr how many people take the world so much for granted that it never bothers th or even crosses their mind. It is true that the human race once occupied an infinitely greater space than this city. You have seen something of what eart was like before the deserts came and the oceans vanished. Those records you are so fond of projecting are the earliest we possess; they are the only on that show earth as it was before the invaders came. I do not imagine that people have ever seen them; those limitless, open spaces are something we cannot bear to contemplate. "And even earth, of course, was only a grain of sand in the galactic empire. What the gulfs between the stars must have been like is a nightmare no sane man would try to imagine. Our ancestors crossed them at the dawn of history when they went out to build the empire. They crossed them again for the last time when the invaders drove them back to earth. "The legend is-and it is only a legend-that we made a pact with th invaders. They could have the universe if they needed it so badly, we would content with the world on which we were born. "We have kept that pact and forgotten the vain dreams of our childhood as you too will forget them, alvi The men who built this city, and designed the society that went with it, we lords of mind as well as matter. They put everything that the human race wo ever need inside these walls-and then made sure that we would never leave them. Oh, the physical barriers are the least important ones. Perhaps there
are routes that lead out of the city, but i do not think you would go alo them for very far, even if you found them. And if you succeeded in the attempt, what good would it do? Your body would not last long in the desert when the city could no longer protect or nourish it." "if there is a route of the city," said alvin slowly, "then what is there to stop me from leavin "that is a foolish question," answered jeserac. "I think you already know the answer." jeserac was right, but not in the way he imagined. Alvin knew-or, rather, he had guessed. His companions had given him the answer, both in the waking life and in the dream adventures he had shared with them. They would never be able to leave diaspar; what jeserac did not know was that the
his
know, bu

this was one of its results. He wondered how many others he had yet to discover. No one ever hurried in diaspar, and this was a rule which even al seldom broke. He considered the problem care-fully for several weeks, and
spent much time searching the earliest of the city's historical memories. For hours on end he would lie, supported by the impalpable arms of an anti-gravi field, while the hypnone projector opened his mind to the past. When the record was finished, the machine would blur and vanish-but still alvin would lie staring into nothing-ness before he came back through the ages to meet reality again. He would see again the endless leagues of blue water, vaster than the land itself, rolling their waves against golden shores. His ears
would ring with the boom of breakers stilled these billion years. He would remember the forests and the prairies, and the strange beasts that had once shared the world with man. Very few of these ancient records existed; it was generally accepted, though none knew the reason why, that somewhere between
the coming of the invaders and the building of diaspar all memories of primitive times had been lost. So com-plete had been the obliteration that it was hard to believe it could have happened by accident alone. Mankind had lo its past, save for a few chronicles that might be wholly leg-endary. Before diaspar there was simply the dawn ages. In that limbo were merged inextricabl together the first men to tame fire and the first to release atomic energy-t first men to build a log canoe and the first to reach the stars. On the f side of this desert of time, they were all neighbors. Alvin had intended to make this trip alone once more, but solitude was not always something that could be arranged in diaspar. He had barely left his room when he encountere alystra, who made no attempt to pretend that her presence was accidental. It had never occurred to alvin that alystra was beautiful, for he had never see human ugliness. When beauty is universal, it loses its power to move the heart, and only its absence can produce any emotional effect. For a moment alvin was annoyed by the meeting, with its reminder of passions that no long moved him. He was still too young and self-reliant to feel the need for any lasting relationships, and when the time came he might find it hard to make them. Even in his most intimate moments, the barrier of his uniqueness came between him and his lovers. For all his fully formed body, he was still a child and would re-main so for decades yet, while his companions one by one recalled the memories of their past lives and left him far behind. He had s it happen before, and it made him wary of giving himself unreservedly to any other person. Even alys-tra, who seemed so naive and artless now, would soon be-come a complex of memories and talents beyond his imagination. His mild annoyance vanished almost at once. There was no reason why alystra should not come with him if she desired. He was not selfish and did not wish to clutc this new experience to his bosom like a miser. Indeed, he might be able to learn much from her reactions. She asked no questions, which was unusual, as the express channel swept them out of the crowded heart of the city. Togethe they worked their way to the central high-speed section, never bothering to glance at the miracle beneath their feet. An engineer of the ancient world would have gone slowly mad trying to understand how an apparently solid
roadway could be fixed at the sides while toward the center it moved at a steadily increasing velocity. But to alvin and alystra, it seemed perfectly natural that types of matter should exist that had the properties of solids one direction and of liquids in another. Around them the buildings rose highe and higher as if the city was strengthening its bulwarks against the outer world. How strange it would be, thought alvin, if these towering walls became as transparent as glass, and one could watch the life within. Scattered throughout the space around him were friends he knew, friends he would one d know, and strangers he would never meet-though there could be very few of these since in the course of his lifetime he would meet almost all the peop in diaspar. Most of them would be sitting in their separate rooms, but they would not be alone. They had only to form the wish and they could be, in but physical fact, in the presence of any other person they chose. They were not bored, for they had access to every thing that had happened in the real

was also a wholly futile one, even alvin did not yet comprehend. As alvin a alystra moved outward from the city's heart, the number of people they saw i the streets slowly decreased, and there was no one in sight when they were brought to a smooth halt against a long platform of brightly colored marble. They stepped across the frozen whirlpool of matter where the substance of the moving way flowed back to its origin, and faced a wall pierced with brightly lighted tunnels. Alvin selected one without hesitation and stepped into it,
with alystra close behind. The peristaltic field seized them at once and propelled them forward as they lay back luxuriously, watching their surroundings. It no longer seemed possible that they were in a tunnel far
underground. The art that had used all of diaspar for its canvas had been b here, and above them the skies seemed open to the winds of heaven. All arou were the spires of the city, gleaming in the sunlight. It was not the city that alvin knew, but the diaspar of a much earlier age. Although most of th great buildings were familiar, there were subtle differences that added to the interest of the scene. Alvin wished he could linger, but he had never found any way of retarding his progress through the tunnel. All too soon they were set gently down in a large elliptical chamber, completely surrounded by
windows. Through these they could catch tantalizing glimpses of gardens ablaze with brilliant flowers. There were gardens still in diaspar, but these had existed only in the mind of the artist who conceived them. Certainly there were no such flowers as these in the world today. Alystra was enchanted by their beauty, and was obviously under the impression that this was what alvin had brought her to see. He watched her for a while as she ran gaily from
to scene, enjoying her delight in each new discovery. There were hundreds of such places in the half-deserted buildings around the periphery of diaspar, kept in perfect order by the hidden powers which watched over them. One day
the tide of life might flow this way once more, but until then this ancient garden was a secret which they alone shared. "We've further to go," said alv at last. "This is only the beginning." he stepped through one of the windows and the illusion was shattered. There was no garden behind the glass, but a circular passageway curving steeply upward. He could still see alystra, a few feet away, though he knew that she could not see him. But she did not hesitate, and a moment later was standing beside him in the passage. Beneath their feet the floor began to creep slowly forward, as if eager to lead the to their goal. They walked along it for a few paces, until their speed was great that further effort would be wasted. The corridor still inclined upward, and in a hundred feet had curved through a complete right angle. But only logic knew this; to all the senses it was as if one was now being hurried along an absolutely level corridor. The fact that they were in reality moving straight up a vertical shaft thousands of feet deep gave them no sense of insecurity, for a failure of the polarizing field was unthinkable. Presently
the corridor began to slope "downward" again until once more it had turned through a right angle. The movement of the floor slowed imperceptibly until i came to rest at the end of a long hall lined with mirrors, and alvin knew there was no hope of hurrying alystra here. It was not merely that some feminine characteristics had survived unchanged since eve; no one could have resisted the fascina-tion of this place. There was nothing like it, as far a alvin knew, in the rest of diaspar. Through some whim of the art-ist, only few of the mirrors reflected the scene as it really was-and even those, alvi was convinced were constantly changing their position. The rest certainly reflected something, but it was faintly disconcerting to see oneself walking amid ever-changing and quite imaginary surroundings. Sometimes there were
people going to and fro in the world behind the mirror, and more than once alvin had seen faces that he recognized. He realized well enough that he had not been looking at any friends he knew in this existence. Through the mind the unknown artist he had been seeing into the past watching the previous incarnations of people who walked the world today. It saddened him, by

reminding him of his own uniqueness, to think that however long he waited before these changing scenes he would never meet any ancient echo of himself. "Do you know where we are?" alvin asked alystra when they had completed the tour of the mirrors. Alystra shook her head. "Somewhere near the edge of the city, i suppose," she answered carelessly. "We seem to have gone a long way, but i've no idea how far." "we're in the tower of loranne," replied alvin. "This is one of the highest points in diaspar. Come-i'll show you." he caugh alystra's hand and led her out of the hall. There were no exits visible to eye, but at various points the pattern on the floor indicated side corridors. As one approached the mirrors at these points, the reflections seemed to fuse into an archway of light and one could step through into another passage. Alystra lost all conscious track of their twistings and turnings, and at last they emerged into a long, perfectly straight tunnel through which blew a cold and stead nd. It stretched horizontally for hundreds of feet in either , direction, and its far ends were tiny circles of light."i don't like this place," alystra complained. "It's cold." She had probably never before experienced real coldness in her life, and alvin felt somewhat guilty. He should have warned her to bring a cloak-and a good one, for all clothes in diaspar were purely ornamental and quite useless as a protection. Since her discomfort was entirely his fault, he handed over his cloak without a word. There was no trace of gallantry in this; the equality of the sexes had been complete for far too long for such conventions to survive. Had matters been the other way around, alystra would have given alvin her cloak and he would have as automatically accepted. It was not unpleasant walking with the wind behind them, and they soon reached the end of the tunnel. A wide-meshed filigree of stone prevented them from going farther, which was just as well, for they stood on the brink of nothingness. The great air duct opened on th sheer face of the tower, and below them was a vertical drop of at least a thousand feet. They were high upon the outer ramparts of the city, and diasp lay spread beneath them as few in their world could ever have seen it. The view was the obverse of the one that alvin had obtained from the center of park. He could look down upon the concentric waves of stone and metal as th descended in mile-long sweeps toward the heart of the city. Far away, partly hidden by the intervening towers, he could glimpse the distant fields and
trees and the eternally circling river. Further still, the remoter bastions of diaspar climbed once more toward the sky. Beside him, alystra was sharing the view with pleasure but with no surprise. She had seen the city countless tim before from other, almost equally well-placed vantage points-and in
considerably more comfort. "That's our world-all of it," said alvin. "Now i want to show you something else." he turned away from the grat-ing and began to walk toward the distant circle of light at the far end of the tunnel. T wind was cold against his lightly clad body, but he scarcely noticed the discomfort as he walked forward into the air stream. He had gone only a lit way when he realized that alystra was making no attempt to follow. She stood watching, her borrowed cloak streaming down the wind, one hand half raised to her face. Alvin saw her lips move, but the words did not reach him. He loo back at her first with astonish-ment then with an impatience that was not totally devoid of pity. What jeserac had said was true. She could not fol-lo him. She had realized the meaning of that remote circle of light from which the wind blew forever into diaspar. Behind alystra was the known world, full of wonder yet empty of surprise, drifting like a brilliant but tightly closed bubble down the river of time. Ahead, separated from her by no more than th span of a few footsteps, was the empty wilderness-the world of the desert-the world of the invaders. Alvin walked back to join her and was surprised to find that she was trembling. "Why are you frightened?" he asked. "We're still safely here in diaspar. You've looked out of that window behind us surely yo can look out of this one as well!" alystra was staring at him as if he wa some strange mon-ster. By her standards, indeed, he was. "I couldn't do it," she said at last. "Even thinking about it makes me feel colder than this wi Don't go any farther, alvin!" "but there's no logic in it!" alvin persisted

remorselessly. "What possible harm would it do you to walk to the end of th corridor and look out? It's strange and lonely out there but it isn't horrible. In fact, the longer i look the more beautiful i think-" alystra di not stay to hear him finish. She turned on her heels and fled back down th long ramp that had brought them up through the floor of this tunnel. Alvin made no attempt to stop her, since that would have involved the bad manners imposing one's will upon another. Persuasion, he could see would have been utterly useless. He knew that alystra would not pause until she had returned to her com-panions. There was no danger that she would lose herself m the labyrinths of the city, for she would have no dif-ficulty in retracing her footsteps. An instinctive ability to extricate himself from even the most complex of mazes had been merely one of the many accomplishments man had learned since he started to live in cities. The long-extinct rat had been forced to acquire similar skills when he left the fields and threw in his l with humanity. Alvin waited for a moment, as if half-expecting alystra to return. He was not surprised at her reaction only at its violence and irrationality. Though he was sincerely sorry that she had gone, he could not help wishing that she had re membered to leave the cloak. It was not only cold, but it was also hard work moving against the wind which sighed through the lungs of the city. Alvin was fighting both the air current and whatever force it was that kept it moving. Not until he had reached the stone grille and could lock his arms around its bars, could he afford to relax. There wa just sufficient room for him to force his head through the opening, and even so his view was slightly restricted, as the entrance to the duct was partly recessed into the city's wall. Yet he could see enough. Thousands of feet below, the sunlight was taking leave of the desert. The almost horizontal ray struck through the grating and threw a weird pattern of gold and shadow far down the tunnel. Alvin shaded his eyes against the glare and peered down at the land upon which no man had walked for unknown ages. He might have been looking at an eternally frozen sea. For mile after mile, the sand dunes undulated into the west, their contours grossly exaggerated by the slanting light. Here and there some caprice of the wind had carved curious whirlpools and gullies in the sand, so that it was sometimes hard to realize that none this sculpture was the work of intelligence. At a very great distance, so fa away indeed that he had no way of judging their remoteness, was a range of softly rounded hills. They had been a disappointment to alvin; he would have given much to have seen in reality the soaring mountains of the ancient records and of his own dreams. The sun lay upon the rim of the hills, its light tamed and reddened by the hundreds of miles of atmosphere it was traversing. There were two great black spots upon its disc; alvin had learned from his studies that such things existed, but he was surprised that he coul see them so easily. They seemed almost like a pair of eyes peering back at as he crouched in his lonely spy hole with the wind whistling ceaselessly pa his ears. There was no twilight. With the going of the sun, the pools of shadow lying among the sand dunes flowed swiftly together in one vast lake o darkness. Color ebbed from the sky; the warm reds and golds drained away leaving an antarctic blue that deepened and deepened into night. Alvin waited for that breathless moment that he alone of all man-kind had known-the moment when the first star shivers into life. It had been many weeks since he had last come to this place, and he knew that the pattern of the night sky mus have changed meanwhile. Even so, he was not prepared for his first glimpse o the seven suns. They could have no other name; the phrase leaped un-bidden t his lips. They formed a tiny, very compact and astonishingly symmetrical group against the afterglow of sun-set. Six of them were arranged in a slightly flattened ellipse, which, alvin was sure, was in reality a perfect circle, slightly tilted toward the line of vision. Each star was a different color; could pick out red, blue, gold, and green, but the other tints eluded his e At the precise center of the forma-tion was a single white giant-the brightes

chance, that naure could ever have contrived so perfect a pattern. As his ey grew slowly accustomed to the darkness, alvin could make out the great misty veil that had once been called the milky way. It stretched from the zenith down to the horizon, and the seven suns were entangled in its folds. The ot stars had now emerged to challenge them, and their random groupings only emphasized the enigma of that perfect symmetry. It was almost as if some pow had de-liberately opposed the disorder of the natural universe by setting its sign upon the stars. Ten times, no more, the galaxy had turned upon its axi since man first walked on earth. By its own standards, that was but a momen Yet in that short period it had changed completely-changed far more than it had any right to do in the natural course of events. The great suns that h once burned so fiercely in the pride of youth were now guttering to their doom. But alvin had never seen the heavens in their ancient glory, and so w unaware of all that had been lost. The cold, seeping through into his bones, drove him back to the city. He extricated himself from the grating and rubbe the circulation back into his limbs. Ahead of him, down the tunnel, the ligh streaming out from diaspar was so brilliant that for a moment he had to ave his eyes. Outside the city there were such things as day and night, but wit it there was only eternal day. As the sun descended the sky above diaspar would fill with light and no one would notice when the natural illumination vanished. Even before men had lost the need for sleep, they had driven darkness from their cities. The only night that ever came to diaspar was a rare and unpredictable obscuration that sometimes visited the park and transformed it into a place of mystery. Alvin came slowly back through the hall of mirrors, his mind still filled with night and stars. He felt inspire and yet depressed. There seemed no way in which he could ever escape out in that enormous emptiness-and no rational purpose in doing so. Jeserac had said that a man would soon die out in the desert, and alvin could well believe Perhaps he might one day discover some way of leaving diaspar, but if he di he knew that he must soon return. To reach the desert would be an amusing game, no more. It was a game he could share with no one, and it would lea nowhere. But at least it would be worth doing if it helped to quench the longing in his soul. As if unwilling to return to the familiar world, alvin lingered among the reflections from the past. He stood before one of the gre mirrors and watched the scenes that came and went within its depths. Whatever mechanism produced these images was controlled by his presence, and to some extent by his thoughts. The mirrors were always blank when he first came int the room, but filled with action as soon as he moved among them. He seemed be standing in a large open courtyard which he had never seen in reality, b which probably still existed somewhere in diaspar. It was unusually crowded,
and some kind of public meeting seemed to be in progress. Two men we arguing politely on a raised platform while their supporters stood around and made interjections from time to time. The complete silence added to the charm of the scene, for imagination immediately went to work supplying the missing sounds. What were they debating? Alvin wondered. Perhaps it was not a real scene from the past, but a purely created episode. The careful balance of figures, the slightly formal movements, all made it seem a little too neat f life. He studied the faces in the crowd, seeking for anyone he could recognize. There was no one here that he knew, but he might be looking at friends he would not meet for cen-turies to come. How many possible patterns of human physiog-nomy were there? The number was enormous, but it was still finite, especially when all the unesthetic variations had been eliminated. The people in the mirror world continued their long-for-gotten argument, ignoring
the image of alvin which stood motionless among them. Sometimes it was very hard to be-lieve that he was not part of the scene himself, for the illu-si was so flawless. When one of the phantoms in the mirror appeared to move behind alvin, it vanished just as a real object would have done; and when o moved in front of him, he was the one who was eclipsed. He was preparing t leave when he noticed an oddly dressed man standing a little apart from the main group. His movements, his clothes, everything about him, seemed slightly

out of place in this assembly. He spoiled the pattern; like alvin, he was a anachronism.he was a good deal more than that. He was real, and he was look at alvin with a slightly quizzical smile. Five In his short lifetime, alv had met less than one-thousandth of the inhabitants of diaspar. He was not surprised, therefore, that the man confronting him was a stranger. What did surprise him was to meet anyone at all here in this de-serted tower, so nea the frontier of the unknown. He turned his back on the mirror world and fac the intruder. Before he could speak, the other had addressed him. "You are alvin, i believe. When i discovered that someone was coming here, i should have guessed it was you." the remark was obviously not intended to give offense; it was a simple statement of fact, and alvin accepted it as such. was not surprised to be recognized; whether he liked it or not, the fact of his uniqueness, and its unrevealed po-tentialities, had made him known to everyone in the city. "I am hedron," continued the stranger, as if that explained everything. "They call me the jester." alvin looked blank, and
khedron shrugged his shoulders in mock resignation. "Ah, such is fame! Still, you are young and there have been no jests in your lifetime. Your ignorance excused." there was something refreshingly unusual about khedron. Alvin
searched his mind for the meaning of the strange word "jester"; it evoked th faintest of memories, but he could not identify it. There were many such titles in the complex social structure of the city, and it took a lifetime learn, them all. "Do you often come here?" alvin asked, a little jealously. had grown to regard the tower of loranne as his personal property and felt slightly annoyed that its marvels were known to anyone else. But had khedron, he wondered, ever looked out across the desert or seen the stars sinking dow into the west? "No," said khedron, almost as if answering his unspoken thoughts. "I have never been here before. But it is my pleasure to learn of unusual happenings in the city ,and it is a very long time since anyone wen to the tower of loranne." Alvin wondered fleetingly how khedron knew of his earlier visits, but quickly dismissed the matter from his mind. Diaspar was full of eyes and ears and other more subtle sense organs which kept the cit aware of all that was happening within it. Anyone who was sufficiently interested could no doubt find a way of tapping these channels. "Even if it unusual for anyone to come here," said alvin, still fencing verbally, "why should you be interested?" "because in diaspar," replied khedron, "the unusual is my prerogative. I had marked you down a long time ago; i knew we should meet some day. After my fashion, i too am unique. Oh not in the way that are; this is not my first life. I have walked a thousand times out of the of creation. But somewhere back at the beginning i was chosen to be jester, and there is only one jester at a time in diaspar. Most people think that one too many." there was an irony about khedron's speech that left alvin sti floundering. It was not the best of manners to ask direct personal questions, but after all khedron had raised the subject. "I'm sorry about my ignorance," said alvin. "But what is a jester, and what does he do?" "you ask 'what,"' replied khedron, "so i'll start by telling you `why.' it's a long story, but think you will be in-terested." "i am interested in everything," said alvin, truthfully enough. "Very well. The men-if they were men, which i sometimes doubt-who designed diaspar had to solve an incredibly complex problem. Diaspar is not merely a machine, you know-n is a living organism and an immortal on We are so ac-customed to our society that we can't appreciate how strange it would have seemed to our first ancestors. Here we have a tiny, closed world which never changes except in its minor details, and yet which is perfectly stable, age after age. It has probably lasted longer than the rest of human history-yet in that history there were, so it is believed, countless
thou-sands of separate cultures and civilizations which endured for a little while and then perished. How did diaspar achieve its extraordinary stability?" alvin was surprised that anyone should ask so elementary a question, and his hopes of learning something new began to wane. "Through the memory banks, of course," he replied. "Diaspar is always composed of the same people, though their actual groupings change as their bodies are created or de-stroyed."

khedron shook his head. "That is only a very small part of the answer. With exactly the same people, you could build many different patterns of society. can't prove that, and i've no direct evidence of it, but i believe it's tru The designers of the city did not merely fix its population; they fixed the laws governing its behavior. We're scarcely aware that those laws exist, but
we obey them. Diaspar is a frozen culture, which cannot change outside of narrow limits. The memory banks store many other things outside the patterns of our bodies and personalities. They store the image of the city itself,
holding its every atom rigid against all the changes that time can bring. Lo at this pavement-it was laid down millions of years ago, and countless feet have walked upon it. Can you see any sign of wear? Unprotected matter, howev adamant, would have been ground to dust ages ago. But as long as there is power to operate the memory banks, and as long as the matrices they contain can still control the patterns of the city, the physical structure of diaspar will never change." but there have been some changes," protested alvin. "Many buildings have been torn down since the city was built, and new ones erected "of course-but only by discharging the information stored in the memory banks and then setting up new patterns. In any case, i was merely mentioning that an example of the way the city preserves itself physically. The point i want to make is that in the same way there are machines in diaspar that preserve our social structure. They watch for any changes, and correct them before the become too great. How do they do it? I don't know-perhaps by selecting those who emerge from the hall of creation. Perhaps by tampering with our
personality patterns we may think we have free will, but can we be certain that?" "in any event, the problem was solved. Diaspar has survived and come safely down the ages, like a great ship carrying as its cargo all that is of the human race. It is a tremendous achievement in social engineering,
though whether it is worth doing is quite another matter. "Stability, however, is not enough. It leads too easily to stagnation, and thence to decadence. T designers of the city took elaborate steps to avoid this though these deserte build-ings suggest that they did not entirely succeed. I, khedron the jester, am part of that plan. A very small part, perhaps. I like to think otherwise but i can never be sure." "and just what is that part?" asked alvin, still very much is the dark, and becoming a little exasperate. "Let us say that i introduce calculated amounts of disorder into the city. To explain my
operations would be to destroy their effectiveness. Judge me by my deeds, though they are few, rather than my words, though they are many." alvin had never before met anyone quite like khedron. The jester was a real
personality-a character who stood head and shoulders above the general level of uniformity which was typical of diaspar. Though there seemed no hope of discovering precisely what his duties were and how he carried them out, that was of minor importance. All that mattered, alvin sensed, was that here was someone to whom he could talk-when there was a gap in the monologue-and who might give him answers to many of the problems that had puzzled him for so long. They went back together down through the corridors of the tower of loranne, and emerged beside the deserted moving way. Not until they were once more in the streets did it occur to alvin that khedron had never asked him what he had been doing out here at the edge of the unknown. He suspected t khedron knew, and was interested but not surprised. Something told him that i would be very difficult to surprise khedron. They exchanged index numbers, so that they could call each other whenever they wished. Alvin was anxious to s more of the jester, though he fancied that his company might prove exhausting if it was too prolonged. Before they met again, however, he wanted to find what his friends, and particularly jeserac could tell him about khedron.
"Until our next meeting," said khedron, and promptly vanished. Alvin was somewhat annoyed. If you met anyone when you were merely projecting yourself, and were not present in the flesh, it was good manners to make that clear the beginning. It could sometimes put the party who was ignorant of the fact at a considerable disadvantage. Probably khedron had been quietly at home all the time wherever his home might be. The number that he had given alvin

would insure that any messages would reach him, but did not reveal where he lived. That at least was according to normal custom. You might be free enoug with index numbers, but your actual address was something you disclosed only
to your intimate friends. As he made his way back into the city, alvin pondered over all that khedron had told him about diaspar and its social organization. It was strange that he had met no one else who had ever seeme dissatisfied with their mode of life. Diaspar and its inhabitants had been designed as part of one master plan; they formed a perfect symbiosis. Throughout their long lives, the people of the city were never bored. Though their world might be a tiny one by the standard of earlier ages, its complexity was overwhelming, its wealth of wonder and treasure beyond calculation. Here man had gathered all the fruits of his genius, everything that had been saved from the ruin of the past. All the cities that had eve been, so it was said, had given something to diaspar; before the coming of invaders, its name had been known on all the worlds that man had lost. Into the building of diaspar had gone all the skill, all the artistry of the empire. When the great days were coming to an end, men of genius had remold the city and given it the machines that made it immortal. Whatever might be forgotten, diaspar would live and bear the descendants of man safely down the stream of time. They had achieved nothing except survival, and were content with that. There were a million things to occupy their lives between the hou when they came, almost full-grown, from the hall of creation and the hour when, their bodies scarcely older, they returned to the memory banks of the city. In a world where all men and women possess an intelligence that would once have been the mark of genius, there can be no danger of boredom. The delights of conversation and argument, the intricate formalities of social intercourse these alone were enough to occupy a goodly portion of a lifetime. Beyond those were the great formal debates, when the whole city would listen entranced while its keenest minds met in combat or strove to scale those mountain peaks of philoso-phy which are never conquered yet whose challenge never palls. No man or woman was without some absorbing intellectual interest. Eriston, for example, spent much of his time in prolonged soliloquies with th central computer, which virtually ran the city, yet which had leisure for scores of simultaneous discussions with anyone who cared to match his wits against it. For three hundred years, eriston had been trying to construct logical paradoxes which the machine could not resolve. He did not expect to make serious progress before he had used up several lifetimes. Etania's interests were of a more esthetic nature. She designed and constructed, with the aid of the matter organi-zers, three-dimensional interlacing patterns of
such beautiful complexity that they were really extremely advanced prob-lems
in topology. Her work could be seen all over diaspar, and some of her patte had been incorporated in the floors of the great halls of choreography, where they were used as the basis for evolving new ballet creations and dance motifs. Such occupations might have seemed arid to those who did not possess the intellect to appreciate their subtleties. Yet there was no one in diaspar who could not understand some-thing of what eriston and etania were trying to do and did not have some equally consuming interest of his own. Athletics an various sports, including many only rendered possible by the control of
gravity, made pleasant the first few centuries of youth. For adventure and th exercise of the imagination, the sagas provided all that anyone could desire. They were the inevitable end product of that striving for realism which began when men started to reproduce moving images and to record sounds, and then t use these techniques to enact scenes from real or imaginary life. In the sagas, the illusion was perfect because all the sense impressions involved
were fed directly into the mind and any conflicting sensations were diverted. The entranced spectator was cut off from reality as long as the adventure lasted; it was as if he lived a dream yet believed he was awake. In a wor order and stability, which in its broad out-lines had not changed for a billion years, it was perhaps not surprising to find an absorbing interest in games of chance. Humanity had always been fascinated by the mystery of the

falling dice, the turn of a card, the spin of the pointer. At its lowest level, this interest was based on mere cupidity-and that was an emotion that could have no place in a world where everyone possessed all that they could reasonably need. Even when this motive was ruled out, however, the purely intellectual fascination of chance remained to seduce the most sophisticated minds. Machines that behaved in a purely ran-dom way-events whose outcome
could never be predicted, no matter how much information one had-from these phi-losopher and gambler could derive equal enjoyment. And there still remained, for all men to share, the linked worlds of love and art. Linked,
because love without art is merely the slaking of desire, and art cannot be enjoyed un-less it is approached with love. Men had sought beauty in many forms-in sequences of sound, in lines upon paper, in surfaces of stone, in t move-ments of the human body, in colors ranged through space. All these media still survived in diaspar, and down the ages others had been added to them. one was yet certain if all the possibilities of art had been discovered; or it had any mean-ing outside the mind of man. And the same was true of
love. Six Jeserac sat motionless within a whirlpool of numbers. The first thousand primes, expressed in the binary scale that had been used for all aritmetical operations since electronic computers were invented, marched in
order before him. Endless ranks of 1's and 0's paraded past, bringing before jeserac's eyes the complete sequence of all those numbers that pos-sessed no factors except themselves and unity. There was a mystery about the primes tha had always fascinated man, and they held his imagination still. Jeserac was n mathematician, though sometimes he liked to believe he was. All he could do was to search among the infinite array of primes for special relationships an rules which more talented men might incorporate in general laws. He could fin how numbers behaved, but he could not ex-plain why. It was his pleasure to hack his way through the arithmetical jungle, and sometimes he discovered wonders that more skillful explorers had missed. He set up the matrix of all possible integers, and started his computer stringing the primes across its surface as beads might be arranged at the intersections of a mesh. Jeserac h done this a hundred times before, and it had never taught him anything. But was fascinated by the way in which the numbers he was studying were scattere apparently ac-cording to no laws, across the spectrum of the integers. He kne the laws of distribution that had already been dis-covered, but always hoped
to discover more. He could scarcely complain about the interruption. If he ha wished to remain undisturbed, he should have set his annunciator accordingly.
As the gentle chime sounded in his ear, the wall of numbers shivered, the digits blurred together, and jeserac returned to the world of mere reality. H recognized khedron at once, and was none too pleased. Jeserac did not care t be disturbed from his ordered way of life, and khedron represented the unpredictable. However, he greeted his visitor politely enough and concealed
all trace of his mild concern. When two people met for the first time in diaspar-or even for the hundredth-it was customary to spend an hour or so in an exchange of courtesies before getting down to business, if any. Khedron somewhat offended jeserac by racing through these formalities in a mere
fifteen minutes and then saying abruptly: "i'd like to talk to you about alvin. You're his tutor, i believe." "that is true," replied jeserac. "I stil see him several times a week-as often as he wishes." "and would you say tha he was an apt pupil?" jeserac thought that over; it was a difficult question to answer. The pupil-tutor relationship was extremely important and was,
indeed, one of the foundations of life in diaspar. On the average, ten thousand new minds came into the city every year. Their previous memories wer still latent, and for the first twenty years of their existence everything around them was fresh and strange. They had to be taught to use the myriad machines and devices that were the background of everyday life, and they had to learn their way through the most complex society man had ever built. Part of this instruction came from the couples chosen to be the parents of the n citizens. The selection was by lot, and the duties were not onerous. Eriston and etania had devoted no more than a third of their time to alvin's

up-bringing, and they had done all that was expected of them. Jeserac's dutie were confined to the more formal aspects of alvin's education; it was assumed that his parents would teach him how to behave in society and introduce him an ever-widening circle of friends. They were responsible for alvin's
character, jeserac for his mind. "I find it rather hard to answer your question," jeserac replied. "Certainly there is nothing wrong with alvin's intelligence, but many of the things that should concern him seem to be a matter of complete indifference. On the other hand, he shows a morbid curiosity regarding subjects which we do not generally discuss." "the world outside diaspar, for example?" "yes-but how did you know?" khedron hesitated for a moment, wondering how far he should take jeserac into his confidence. knew that jeserac was kindly and well-intentioned, but he knew also that he
must be bound by the same taboos that controlled every-one in diaspar-everyone except alvin. "I guessed it," he said at last. Jeserac settled down more comfortably in the depths of the chair he had just materialized. This was an interesting situation, and he wanted to analyze it as fully as possible. Ther was not much he could learn, however, unless khedron was willing to
co-operate. He should have anticipated that alvin would one day meet the jester, with unpredictable consequences. Khedron was the only other person in the city who could be called eccentric-and even his eccentricity had been planned by the designers of diaspar. Long ago it had been discovered that without some crime or disorder, utopia soon became un-bearably dull. Crime, however, from the nature of things, could not be guaranteed to remain at the optimum level which the social equation demanded. If it was licensed and regulated, it ceased to be crime. The office of jester was the solution-as first sight naive, yet actually profoundly subtle which the city's designers
had evolved. In all the history of diaspar there were less than two hundred persons whose mental inheritance fitted them for this peculiar role. They had certain privileges that protected them from the consequences of their actions, though there had been jesters who had overstepped the mark and paid the only penalty that diaspar could impose-that of being banished into the future
before their current incarnation had ended. On rare and unforeseeable occasions, the jester would turn the city upside-down by some prank which might be no more than an elaborate practical joke, or which might be a calculated assault on some currently cherished belief or way of life. All things considered, the name "jester" was a highly appropriate one. There had once been men with very similar duties, operating with the same license, in
the days when there were courts and kings. "It will help," said jeserac, "if we are frank with one another. We both know that alvin is a unique that he never experienced any earlier life in diaspar. Perhaps you can guess, better than i can, the implications of that. I doubt if anything that happens in t city is totally unplanned, so there must be a purpose in his creation. Wheth he will achieve that purpose-whatever it is-i do not know. Nor do i know whether it is good or bad. I cannot guess what it is." "suppose it concerns something external to the city?" jeserac smiled patiently; the jester was
having his little joke, as was only to be expected. "I have told him what there; he knows that there is nothing outside diaspar except the desert. Take him there if you can; perhaps you know a way. When he sees the reality, it cure the strangeness in his mind." "i think be has already seen it," said khedron softly. But he said it to himself, and not to jeserac. "I do not believe that alvin is happy," jeserac continued. "He has formed no real attachments, and it is hard to see how he can while he still suffers from obsession. But after all, he is very young. He may grow out of this phase, become part of the pattern of the city." Jeserac was talking to reassure himself; khedron wondered if he really believed what he was saying. "Tell me, jeserac," asked khedron abruptly, "does alvin know that be is not the first unique?" jeserac looked startled, then a little defiant. "I might have
guessed," he said ruefully, "that you would know that. How many uniques have there been in the whole history of diaspar? As many as ten?" "fourteen," answered khedron without hesitation. "Not counting alvin." "you have better

information than i can command," said jeserac wryly. "Perhaps you can tell me what happened to those uniques?" "they disappeared." "thank you: i knew that already. That is why i have told alvin as little as possible about his predecessors: it would hardly help him in his present mood. Can i rely on y co-operation?" "for the moment-yes. I want to study him myself; mysteries have always intrigued me, and there are too few in diaspar. Besides, i think that fate may be arranging a jest beside which all my efforts will look very mod indeed. In that case, i want to make sure that i am present at its climax. "you are rather too fond of talking in riddles," complained jeserac. "Exactly what are you anticipating?" "i doubt if my guesses will be any better than yours. But i believe this-neither you nor i nor anyone in diaspar will be a to stop alvin when he has decided what he wants to do. We have a very interesting few centuries ahead of us." jeserac sat motionless for a long
time, his mathematics forgotten, after the image of khedron had faded from sight. A sense of foreboding, the like of which he had never known before, hung heavily upon him. For a fleeting moment he wondered if be should reques an audience with the council -but would that not be making a ridiculous fuss about noth-ing? Perhaps the whole affair was some complicated and ob-scure
jest of khedron's, though he could not imagine why he had been chosen to be its butt. He thought the matter over carefully, examining the prob-lem from every angle. After little more than an hour, he made a characteristic
decision. He would wait and see. Alvin wasted no time learning all that he could about khedron. Jeserac, as usual, was his main source of information.
The old tutor gave a carefully factual account of his meeting with the jeste and added what little he knew about the other's mode of life. Insofar as su a thing was possible in diaspar, khedron was a recluse: no one knew where h lived or anything about his way of life. The last jest he had contrived had been a rather childish prank involving a general paralysis of the moving ways That had been fifty years ago; a century earlier he had let loose a particularly revolting dragon which had wandered around the city eating every existing specimen of the works of the currently most popular sculptor. The artist himself, justifiably alarmed when the beast's single-minded diet became obvious, had gone into hiding and not emerged until the monster had vanished as mysteriously as it had appeared. One thing was obvious from these accounts Khedron must have a profound understanding of the machines and powers that ruled the city, and could make them obey his will in ways which no one els could do. Presumably there must be some overriding control which prevented any too-ambitious jester from causing permanent and irreparable damage to the
complex structure of diaspar. Alvin filed all this information away, but made no move to contact khedron. Though he had many questions to ask the jester, his stubborn streak of independence-perhaps the most truly unique of all his qualities-made him determined to discover all he could by his own unaided efforts. He had embarked on a project that might keep him busy for years, b as long as he felt that he was moving toward his goal he was happy. Like traveler of old mapping out an unknown land, he had begun the systematic exploration of diaspar. He spent his weeks and days prowling through the
lonely towers at the margin of the city, m the hope that somewhere he might dis-cover a way out into the world beyond. During the course of his search found a dozen of the great air vents opening high above the desert, but the were all barred-and even if the bars had not been there, the sheer drop of almost a mile was sufficient obstacle. He found no other exits, though he explored a thousand corridors and ten thousand empty chambers. All these buildings were in that perfect and spotless condition which the people of diaspar took for granted as part of the normal order of things. Sometimes alvin would meet a wandering robot, obviously on a tour of inspection, and h never failed to question the machine. He learned nothing, because the machines he encountered were not keyed to respond to human speech or thoughts. Though they were aware of his presence, for they floated politely aside to let him pass, they refused to engage in conversation. There were times when alvin did not see another human being for days. When he felt hungry, he would go into

one of the living apartments and order a meal. Miraculous machines to whose existence he seldom gave a thought would wake to life after aeons of slumber The patterns they had stored in their memories would flicker on the edge of reality, organizing and directing the matter they controlled. And so a meal prepared by a master chef a hundred million years before would be called aga into existence to delight the palate or merely to satisfy the appetite. The loneliness of this deserted world-the empty shell sur-rounding the living
heart of the city-did not depress alvin. He was used to loneliness, even whe he was among those he called his friends. This ardent exploration, absorbing all his energy and interest, made him forget for the moment the mystery of heritage and the anomaly that cut him off from all his fellows. He had explored less than one-hundredth of the city's rim when he deeded that he wa wasting his time. His decision was not the result of impatience, but of shee common sense. If needs be, he was prepared to come back and finish the task even if it took him the remainder of his life. He had seen enough, however, convince him that if a way out of diaspar did exist, it would not be found easily as this. He might waste centuries in fruitless search unless he called upon the assistance of wiser men. Jeserac had told him flatly that he knew road out of diaspar, and doubted if one existed. The information machines,
when alvin had questioned them, had searched their almost infinite memories in vain. They could tell him every detail of the city's history back to the beginning of recorded times-back to the barrier beyond which the dawn ages la forever hidden. But they could not answer alvin's simple question, or else
some higher power had forbidden them to do so. He would have to see khedron again. Seven "You took your time," said khedron, "but i knew you would c sooner or later." this confidence annoyed alvin; he did not like to think th his behavior could be predicted so accurately. He won-dered if the jester had watched all his fruitless searching and knew exactly what he had been doing. "I am trying to find a way out of the city," he said bluntly. "There must one, and i think you could help me find it." khedron was silent for a mome There was still time, if he wished, to turn back from the road that stretch be-fore him, and which led into a future beyond all his powers of prophecy. one else would have hesitated; no other man in the city, even if he had th power, would have dared to disturb the ghosts of an age that had been dead millions of centuries. Perhaps there was no danger, perhaps nothing could
alter the perpetual changelessness of diaspar. But if there was any risk of something strange and new coming in-to the world, this might be the last chance to ward it off. Khedron was content with the order of things as it True, he might upset that order from time to time but only by a little. He a critic, not a revolutionary. On the placidly flowing river of time, he wished only to make a few ripples: he shrank from diverting its course. The desire for adventure, other than that of the mind, had been eliminated from him as carefully and thoroughly as from all the other citizens of diaspar. Y he still possessed, though it was almost extinguished, that spark of curiosity that was once man's greatest gift. He was still prepared to take a risk. He looked at alvin and tried to remember his own youth, his own dreams of half thousand years before. Any moment of his past that he cared to choose was still clear and sharp when he turned his memory upon it. Like beads upon a string, this life and all the ones before it stretched back through the ages he could seize and re-examine any one he wished. Most of those older khedron were strangers to him now; the basic patterns might be the same, but the weight of experience sepa-rated him from them forever. If he wished, he could wash his mind clear of all his earlier incarnations, when next he walked bac into the hall of creation to sleep until the city called him forth again. B that would be a kind of death, and he was not ready for that yet. He was prepared to go on collecting all that life could offer, like a chambered nautilus patiently adding new cells to its slowly expanding spiral. In his youth, he had been no different from his companions. It was not until he ca of age and the latent memories of his earlier lives came flooding back that had taken up the role for which he had been destined long ago. Sometimes he

felt resentment that the intelligences which had contrived diaspar with such infinite skill could even now, after all these ages, make him move like a puppet across their stage. Here, perhaps, was a chance of obtaining a
long-delayed revenge. A new actor had appeared who might ring down the curtai for the last time on a play that already had seen far too many acts. Sympa for one whose loneliness must be even greater than his own; an ennui produce by ages of repetition; and an impish sense of fun-these were the discordant factors that prompted khedron to act. "I may be able to help you," he told alvin, "or i may not. I don't wish to raise any false hopes. Meet me in h an hour at the intersection of radius 3 and ring 2. If i cannot do anythin else, at least i can promise you an interesting journey. Alvin was at the rendezvous ten minutes ahead of time, though it was on the other side of th city. He waited impatiently as the moving ways swept eternally past him, bearing the placid and contented people of the city about their unimportant business. At last he saw the tall figure of khe-dron appear in the distance, and a moment later he was for the first time in the physical presence of t jester. This was no projected image; when they touched palms in the ancient greeting, khedron was real enough. The jester sat down on one of the marble balustrades and regarded alvin with a curious intentness. "I wonder," he said, "if you know what you are asking. And i wonder what you would do if you obtained it. Do you really imagine that you could leave the city, even if y found a way?" i am sure of it," replied alvin, bravely enough, though khedro could sense the uncertainty in his voice. "Then let me tell you something which you may not know. You see those towers there?" khedron pointed to the twin peaks of power central and council hall, staring at each other across a canyon a mile deep. "Suppose i were to lay a perfectly firm plank between those two towers-a plank only six inches wide. Could you walk across it?" alvin hesitated. "I don't know," he answered. "I wouldn't like to try." "i'm quite sure you could never do it. You'd get giddy and fall off before you'd gone a dozen paces. Yet if that same plank was supported just clear of the ground, you'd be able to walk along it without difficulty." "and what does that prove?" "a simple point i'm trying to make. In the two experiments i've described, the plank would be exactly the same in both cases. One of those wheeled robots you sometimes meet could cross it just as easily if it was bridging those towers as if it was laid along the ground. We couldn't, becau we have a fear of heights. It may be irrational, but it's too powerful to ignored. It is built into us; we are born with it. In the same way, we ha fear of space. Show any man in diaspar a road out of the city-a road that might be just like this road in front of us now-and he could not go far a it. He would have to turn back, as you would turn back if you started to
a plank between those towers." "but why?" asked alvin. "There must have been time-" "i know, i know," said khedron. "Men once went out over the whole wo and to the stars themselves. Something changed them and gave them this fear with which they are now born. You alone imagine that you do not possess it. Well, we shall see. I'm taking you to council hall." the hall was one of t largest buildings in the city, and was almost entirely given over to the machines that were the real administrators of diaspar. Not far from its summi was the chamber where the council met on those infrequent oc-casions when it had any business to discuss. The wide entrance swallowed them up, and khedron strode forward into the golden gloom. Alvin had never entered coun-cil hall before; there was no rule against it-there were few rules against anything in diaspar-but like everyone else he had a certain half-religious awe of the place. In a world that had no gods, council hall was the nearest thing to temple. Khedron never hesitated as he led alvin along corridors and down ramp that were obviously made for wheeled ma-chines, not human traffic. Some of these ramps zigzagged down into the depths at such steep angles that it woul have been impossible to keep a footing on them had not gravity been twisted compensate for the slope. They came at last to a closed door, which slid silently open as they approached, then barred their retreat. Ahead was another door, which did not open as they came up to it. Khedron made no move to t

the door, but stood motionless in front of it. After a short pause, a quiet voice said: "please state your names." i am khedron the jester. My companion is alvin." "and your business?" "sheer curiosity." rather to alvin's surprise, the door opened at once. In his experience, if one gave facetious replies to machines it always led to confusion and one had to go back to the beginning The machine that had interrogated khedron must have been a very sophisticated one-far up in the hierarchy of the central computer. They met no more barrie but alvin suspected that they had passed many tests of which he had no knowledge. A short corridor brought them out abruptly into a huge circular
cham-ber with a sunken floor, and set in that floor was something so astonishing that for a moment alvin was overwhelmed with wonder. He was
looking down upon the entire city of diaspar, spread out before him with its tallest buildings barely reaching to his shoulder. He spent so long picking
out familiar places and observing unexpected vistas that it was some time before he paid any notice to the rest of the chamber. Its walls were covere with a microscopically detailed pattern of black and white squares; the
pattern itself was completely irregular, and when he moved his eyes quickly h got the impression hat it was flickering swiftly, though it never changed. At frequent intervals around the chamber were manually controlled machines of
some type, each complete with a vision screen and a seat for the operator. Khedron let alvin look his fill. Then he pointed to the diminutive city and said: "do you know what that is?" a1vin was tempted to answer, "a model, i suppose," but that answer was so obvious that be was sure it must be wrong. be shook his head and waited for khedron to answer his own question. "You remember," said the jester, "that i once told you how the city was
maintained-how he memory banks hold its pattern frozen forever. Those banks
are all around us, with all their immeasurable store of information completely defining the city as it is today. Every atom of diaspar is somehow keyed, b forces we have forgotten, to the matrices buried in these walls." he waved toward the perfect, infinitely detailed simulacrum of diaspar that lay below them. "That is no model; it does not really exist. It is merely the project image of the pattern held in the memory banks, and therefore it is absolutel identical with the city itself. These viewing machines here enable one to magnify any desired portion, to look at it life size or larger. They are us when it is necessary to make alterations in the design, though it is a very long time since that was done. If you want to know what diaspar is like, t is the place to come. You can learn more here in a few days than you woul a lifetime of actual exploring." "it's wonderful," said alvin. "How many
people know that it exists?' "oh, a good many, but it seldom concerns them. The council comes down here from time to time; no alterations to the city c be made unless they are all here. And not even then, if the central compute doesn't approve of the proposed change. I doubt if this room is visited more than two or three times a year." alvin wanted to know how khedron had acces to it, and then remembered that many of his more elaborate jests must have involved a knowledge of the city's inner mechanisms that could have come only from very profound study. It must be one of the jester's privileges to go anywhere and learn anything; he could have no better guide to the secrets of diaspar. What you are looking for may not exist," said khedron, "but if it does, this is where you will find it. Let me show you how to operate the monitors." for the next hour alvin sat before one of the vision screens, learning to use the controls. He could select at will any point in the city and examine it with any degree of magnification. Streets and towers and walls and moving ways flashed across the screen as he changed the co-ordinates; it was as though he was an all-seeing, disembodied spirit that could move effortlessly over the whole of diaspar, unhindered by any physical
obstructions. Yet it was not, in reality, diaspar that he was examining. Yet moving through the memory cells looking at the dream image of the city-the dream that had had the power to hold the real diaspar untouched by time for billion years. He could see only that part of the city which was permanent; the people who walked its streets were no part of this frozen image. For hi

purpose, that did not matter. His concern now was purely with the creation o stone and metal in which he was imprisoned, and not those who shared-however willingly -his confinement. He searched for and presently found the tower of loranne, and moved swiftly through the corridors and passageways which he had already explored in reality. As the image of the stone grille expanded before his eyes, he could almost feel the cold wind that had blown ceaselessly through it for per-haps half the entire history of mankind, and that was blowing now. He came up to the grille, looked out-and saw nothing. For a moment the shock was so great that he almost doubted his own memory; had hi vision of the desert been nothing more than a dream? Then he remembered the truth. The desert was no part of diaspar, and therefore no image of it exis in the phantom world he was exploring. Anything might lie beyond that grille in reality; this monitor screen could never show it. Yet it could show him something that no living man had ever seen. Alvin advanced his viewpoint through the grille, out into the nothingness beyond the city. He turned the control which altered the direction of vision, so that he looked back-ward along the way that he had come. And there behind him lay diaspar-seen from outside. To the computers, the memory circuits, and all the multitudinous mechanisms that created the image at which alvin was looking, it was merely simple problem of perspective. They "knew" the form of the city; therefore
they could show it as it would appear from the outside. Yet even though he could appreciate how the trick was done, the effect on alvin was overwhelming In spirit, if not in reality, he had escaped from the city. He appeared to hanging in space, a few feet away from the sheer wall of the tower of lora For a moment he stared at the smooth gray surface before his eyes; then he touched the control and let his viewpoint drop toward the ground. Now that h knew the possibilities of this wonderful instru-ment, his plan of action was clear. There was no need to spend months and years exploring diaspar from th inside, room by room and corridor by corridor. From this new van-tage point could wing his way along the outside of the city, and could see at once an openings that might lead to the desert and the world beyond. The sense of victory, of achievement, made him feel light-headed and anxious to share his joy. He turned to khedron, wishing to thank the jester for having made this possible. But khedron was gone, and it took only a moments thought to realiz why. Alvin was perhaps the only man in diaspar who could look unaffected upo the images that were now drifting across the screen. Khedron could help him his search, but even the jester shared the strange terror of the universe which had pinned mankind for so long inside its little world. He had left alvin to continue his quest alone. The sense of loneliness, which for a litt while had lifted from alvin's soul, pressed down upon him once more. But thi was no time for melancholy; there was too much to do. He turned back to th monitor screen, set the image of the city wall drifting slowly across it, an began his search. Diaspar saw little of alvin for the next few weeks, thou only a few people noticed his absence. Jeserac, when he discovered that his erstwhile pupil was spending all his time at council hall instead of prowling around the frontier of the city, felt slightly relieved, imagining that alvin could come to no trouble there. Eriston and etania called his room once or twice, found that he was out and thought nothing of it. Alystra was a littl more persistent. For her own peace of mind, it was a pity that she had b infatuated with alvin, when there were so many more suitable choices. Alystra had never had any difficulty in find-ing partners, but by comparison with
alvin all the other men she knew were nonentities, cast from the same featureless mold. She would not lose him without a struggle: his aloofness an indifference set a challenge which she could not resist. Yet perhaps her motives were not entirely selfish, and were maternal rather than sexual.
Though birth had been forgotten, the feminine instincts of protection and sympathy still remained. Alvin might appear to be stubborn and self-reliant and determined to have his own way, yet alystra could sense his inner loneliness. When she found that alvin had disappeared, she promptly asked jeserac what had happened to him. Jeserac, with only a momentary hesitation,

told her. If alvin did not want company, the answer was in his own hands. tutor neither approved nor disapproved of this relationship. On the whole, he rather liked alystra and hoped that her influence would help alvin to adjust himself to life in diaspar. The fact that alvin was spending his time at council hall could only mean that he was engaged on some research project, a this knowledge at least served to quell any suspicions alystra might have concerning possible rivals. But though her jealousy was not aroused, her curiosity was. She sometimes reproached herself for abandoning alvin in the tower of loranne though she knew that if the circumstances were re-peated she would do exactly the same thing again. There was no way of understanding alvin's mind, she told herself, un-less she could discover what he was trying to do. She walked purposefully into the main hall, impressed but not overawed by the hush that fell as soon as she passed through the entrance. The information machines were range side by side against the far wall, and she chose one at random. As soon as the recognition signal lighted up she said, am looking for alvin; he is somewhere in this building. Where can i find hi even after a lifetime, one never grew wholly accustomed to the complete
absence of time lag when an information ma i chine replied to an ordinary question. There were people w hp knew-or claimed to know-how it was done, an talked, learnedly of "access time" and "storage space," but that made the
final result none the less marvelous. Any question of a 1 purely factual nature, within the city's truly enormous range of available information, could be answered immediately. Only if complex calculations were involved before a reply could be given would there be any appreciable delay. "He is with the monitors," came the reply. It was not very helpful, since the name conveyed nothing to alystra. No machine ever volunteered more information than it was asked for, and learning to frame questions properly was an art which often took a long time to acquire. "How do i reach him?" asked alystra. She would find what the monitors were when she got to them. "I cannot tell you unless you have the permission of the council."this was a most unexpected, even a disconcerting, development. There were very few places in diaspar that could
not be visited by anyone who pleased. Alystra was quite certain that alvin h not obtained council permission, and this could only mean that a higher authority was helping him. The council ruled diaspar, but the council itself could be overridden by a superior power-the all-but-infinite intellect. Of the central computer. It was difficult not to think of the central computer as a living entity, localized in a single spot, though actually it was the sum total of all the machines in diaspar. Even if it was not alive in the biological sense, it certainly possessed at least as much awareness and
self-consciousness as a human being. It must know what alvin was doing, and, therefore, it must approve, otherwise it would have stopped him or referred
him to the council, as the in-formation machine had done to alystra. There w no point in staying here. Alystra knew that any attempt to find alvin-even i she knew exactly where he was in this enormous building-would be doomed to failure. Doors would fail to open; slideways would reverse when she stood on them, carrying her backward instead of forward; elevator fields would be mysteriously inert, refusing to lift her from one floor to another. If she persisted, she would be gently i conveyed out into the street by a polite b firm robot, or else shuttled round and round council hall until she grew fed up and left under her own volition. She was in a bad temper as she walke into the street. She was also more than a little puzzled, and for the first time felt that there was some mystery here which made her per-sonal desires and interests seem very trivial indeed. That did not mean that they would be any the less important to her. She had no idea what she was going to do n but she was sure of one thing. Alvin was not the only person in diaspar wh could be stubborn and persistent. Eight The image on the monitor screen faded as alvin raised his hands from the control panel and cleared the circuits. For a moment he sat quite motionless, looking into the blank
rec-tangle that had occupied all his conscious mind for so many weeks. He ha circumnavigated his world; across that screen had passed every square foot of

the outer wall of diaspar. He knew the city better than any living man save perhaps iche-dron; and he knew now that there was no way through the walls. The feeling that possessed him was not mere despondency; be had never really expected that it would be as easy as this, that he would find what he soug at the first attempt. What was important was that he had eliminated one possibility. Now he must deal with the others. He rose to his feet and walk over to the image of the city which almost filled the chamber. It was hard to think of it as an actual model, though he knew that in reality it was more than an optical projection of the pattern in the memory cells he had b exploring. When he altered the monitor controls and set his viewpoint moving through dias-par, a spot of light would travel over the surface of this
rep-lica, so that he could see exactly where he was going. It had been a useful guide in the early days, but he soon had grown so skillful at settin the co-ordinates that he had not needed this aid. The city lay spread out beneath him; he looked down upon it like a god. Yet he scarcely saw it as considered, one by one, the steps he should now take. If all else failed, there was one solution to the problem. Diaspar might be held in a perpetual stasis by its eternity circuits frozen forever according to the pattern in th memory cells, but that pattern could itself be altered, and the city would then change with it. It would be possible to redesign a section of the oute wall so that it contained a doorw feed this pattern into the monitors, and the city resh itself to the new conception. Alvin suspected that the large areas of the monitor control board whose purpose khedron had not explained to him concerned with such alterations. It would be useless to periment with
them; controls that could alter the very structure of the city were firmly locked and could be operated only with the authority of the council and the approval the central computer. There was very little chance that council would grant him what he asked, even if he was prepared for decades or even centur of patient pleading. This was not a prospect that appealed to him in the least. He turned his thoughts toward the sky. Sometimes he imagined, in fantasies which he was half-ashamed to recall that he had regained the freedo of the air which man h renounced so long ago. Once, he knew, the skies of earth ha been filled with strange shapes. Out of space the great ships had come, bearing unknown treasures, to berth at the legendary port of diaspar.
But the port had been beyond the limits of the city; aeons ago it had been buried by the drifting sand he could dream that somewhere in the mazes of diaspar flying machine might still be hidden, but he did not really lieve it Even in the days when small, personal flyers had bee in common use, it was most unlikely that they had ever be 1 allowed to operate inside the limits the city. For a moment he lost himself in the old, familiar dream. He imagined that he was master of the sky, that the world lay spread out benea him, inviting him to travel where hewilled. It was not the world of his own time that he saw, but the lost world of the dawn-a rich and living panorama hills and lakes and forests. He felt a bitter envy of his unknown ancestors, who had flown with such freedom over the earth and who had let its beauty This mind-drugging reverie was useless; he tore himself back to the present
and to the problem at hand. If the sky was unattainable and the way by lan was barred, what remained? Once again he had come to the point when he need help, when he could make no further progress by his own efforts he disliked admitting the fact, but was honest enough not deny it. Inevitably, his
thoughts turned to khedron. Alvin had never been able to decide whether he liked the jester. He was very glad that they had met, and was grateful to khedron for the assistance and implicit sympathy he had given him on his quest. There was no one else in diaspar with whom he had so much in common yet there was some element in the other's personality that jarred upon him. Perhap it was khedron's air of ironic detachment, which sometime gave alvin
the impression that he was laughing secretly at all his efforts, even while seemed to be doing his best to help. Because of this, as well as his own natural stubbornness and independence, alvin hesitated to approach the jester except as a last resort. They arranged to meet in a small, circular court n

far from council hall. There were many such secluded spots in the city, perhaps only a few yards from some busy thoroughfare, yet completely cut off from it. Usually they could be reached only on foot after a rather roundabou walk; some-times, indeed, they were at the center of skillfully contrived
mazes which enhanced their isolation. It was rather typical of khedron that h should have chosen such a place for a rendevous. The court was little more than fifty paces across, and was in reality located deep within the interior of some great building. Yet it appeared to have no definite physical limits, being bounded by a translucent blue-green material which glowed with a faint internal light. However, though there were no visible limits, the court had been so laid out that there was no danger of feeling lost in infinite space Low walls, less than waist high and broken at intervals so that one could p through them managed to give the impression of safe con-finement without which no one in diaspar could ever feel entirely happy. Khedron was examining one these walls when alvin arrived. It was covered with an intricate mosaic of colored tiles, so fantastically involved that alvin did not even attempt to unravel it. "Look at this mosaic, alvin," said the jester. "Do you notice anything strange about it?" "no," confessed alvin after a brief examination.
"I don't care for it-but there's nothing strange about that." khedron ran his fingers over the colored tiles. "You are not very observant," he said. "Look at these edges here-see how they become rounded and softened. This is
something that one very seldom sees in diaspar, alvin. It is wear-the
crumbling away of matter under the assault of time. I can remember when this pattern was new, only eighty thousand years ago, in my last lifetime. If i come back to this spot a dozen lives from now, these tiles will have been completely away." "i don't see anything very surprising about that," answered alvin. "There are other works of art in the city not good enough to be preserved in the memory circuits, but not bad enough to be destroyed outright One day, i suppose, some other artist will come along and do a better job. his work won't be allowed to wear out." "i knew the man who designed this wall," said khedron, his fingers still exploring the cracks in the mosaic. "Strange that i can remember that fact, when i don't recall the man himself. could not have liked him, so i must have erased him from my mind." he gave short laugh. "Perhaps i designed it myself, during one of my artistic phases, and was so annoyed when the city refused to make it eternal that i decided forget the whole affair. There i knew that piece was coming loosel" he had managed to pull out a single flake of golden tile, and looked very pleased this minor sabotage. He threw the fragment on the ground, adding, "now the maintenance robots will have to do something about it!" there was a lesson f him here, alvin knew. That strange instinct known as intuition, which seemed
to follow short cuts not accessible to mere logic, told him that. He looked the golden shard lying at his feet, trying to link it somehow to the proble that now dominated his mind. It was not hard to find the answer, once he realized that it existed. Khedron "i see what you are trying to tell me," h said to khedron. "There are objects in diaspar that aren't preserved in the memory circuits, so i could never find them through the monitors at council hall. If i was to go there and focus on this court, there would be no sig the wall we're sitting on." "i think you might find the wall. But there wou be no mosaic on it." "yes, i can see that," said arvin, too impatient now bother about such hairsplitting. "And in the same way, parts of the city mig exist that had never been preserved in the eternity circuits, but which hadn' yet worn away. Still, i don't really see how that helps me. I know that th outer wall exists-and that it has no openings in it." "perhaps there is no out, answered khedron. "I can promise you nothing. But i think there is stil a great deal that the monitors can teach us-if the central computer will let them. And it seems to have taken rather a liking to you. Arvin pondered ove this remark on their way to council hall. Until now, he had assumed that it was entirely through khedron's influence that he had been able to gain access to the monitors. It had not occurred to him that it might be through some intrinsic quality of his own. Being a unique had many disadvantages; it was

only right that it should have some compensations. The unchanging image of th city still dominated the chamber in which arvin had spent so many hours. He looked at it now with a new understanding; all that he saw here existed-but all of diaspar might not be mirrored. Yet, surely, any discordancies must be trivial, and, as far as he could see, undetectable. I attempted to do this many years ago," said khedron, as he sat down at the monitor desk, but the controls were locked against me. Perhaps they will obey me now." slowly, and then with mounting confidence as he regained of the wall we're sitting access to long-forgotten skills, khedron's fingertips moved over the control desk, resting for a moment at the nodal points in the sensitive grid buried in th panel before him. "I think that's correct," he said at last. "Anyway we'll soon see." the screen glowed into life, but instead of the picture that alvi had expected, there appeared a somewhat baffling message: Regression will commence as soon as you have set rate control "Foolish of me," muttered khedron. "I got everything else right and forgot the most important thing of all." his fingers now moved with a confident assurance over the board, and a the message faded from the screen he swung around in his seat so that he c look at the replica of the city. "Watch this, alvin," he said. "I think we both going to learn something new about diaspar." arvin waited patiently, but nothing happened. The image of the city floated there before his eyes in all its familiar wonder and beauty-though he was conscious of neither now. He was about to ask khedron what he should look for when a sudden movement caught attention, and he turned his head quickly to follow it. It had been no more than a half-glimpsed flash or flicker, and he was too late to see what had made it. Nothing had altered; diasnar was just as he had al-ways known it. Then he saw that khedron was watching him with a sardonic smile, so he look again at the city. This time, the thing happened before his eyes. One of th buildings at the edge of the park suddenly vanished, and was replaced
instantly by another of quite dif-ferent design. The transformation was so abrupt that had arvin been blinking he would have missed it. He stared in amazement at the subtly altered city, but even during the first shock of astonishment his mind was seeking for the answer. He remembered the words tha had appeared on the monitor screen-regression will commence-and he knew at
once what was happening. "That's, the city as it was thousands of years ago, he said to khedrn. "We're going back in time." "a picturesque but hardly accurate way of putting it," re-plied the jester. "What is actually happening is that the monitor is remembering the earlier versions of the city. When an modifications were made, the memory circuits were not simply emptied; the information in them was taken to subsidiary storage units, so that it could recalled whenever needed. I have set the monitor to regress through those
units at the rate of a thousand years a second. Already, we're looking at t diaspar of half a million years ago. We'll have to go much farther back tha that to see any real changes-i'11 increase the rate." he turned back to the control board, and even as he did so, not one building but a whole block whipped out of exis•tence and was replaced by a large oval amphitheater. "Ali the arena!" said khedron. "I can remember the fuss when we decided to get r of that. It was hardly ever used, but a great many people felt sentimental about it." the monitor was now recalling its memories at a far higher rate; the image of diaspar was receding into the past at mil•lions of years a minute, and changes were occurring so rapid•ly that the eye could not keep u with them. Alvin noticed that the alterations to the city appeared to come i cycles; there would be a long period of stasis, then a whole rash of , rebuilding would break out, followed by another pause. It was almost as if diaspar were a living organism, which had to re•gain its strength after each explosion of growth. Through all these changes, the basic design of the city had not altered. Buildings came and went, but the pattern of streets seemed eternal, and the park remained as the green heart of. Diaspar. Alvin wondered how far back the monitor could go. Could it return to the founding of the city, and pass through the veil that sundered known history from the myths a leg•ends of the dawn? Already they had gone five hundred million years into

the past. Outside the walls of diaspar, beyond the knowledge of the monitors, it would be a different earth. Perhaps there might be oceans and forests, ev other cities which man had not yet deserted in the long retreat to his fina home. The minutes drifted past, each minute an aeon in the little universe o the monitors. Soon, thought alvin, the earliest of all these stored memories must be reached and the regres•sion would end. But fascinating though this lesson was, he q did not see how it could help him to escape from the cit it was here and now. With a sudden, soundless implosion, diaspar contracted t a fraction of its former size. The park vanished; the boundary wall of linke titanic towers instantly evaporated. This city was open to the world, for the radial roads stretched out to , the limits of the monitor image without obstruction. Here was diaspar as it had been before the great change came up mankind. ~~ "We can go no farther," said khedron, pointing to the monitor screen. On it had appeared the words: regression concluded. "This must be the earliest version of the city that has been preserved in the memory cells. Before that, i doubt if the eternity circuits were used, and the buildings were al•lowed to wear out naturally." for a long time, alvin stared at this model of the ancient city. He thought of the traffic those roads had borne, men came and went freely to all the corners of the world-and to other world as well. Those men were his ancestors; he felt a closer kinship to them tha to the people who now shared his life. He wished that he could see them an share their thoughts, as they moved through the streets of that
billion•year-remote diaspar. Yet those thoughts could not have been happy
ones, for they must have been living then beneath the shadow of the invaders In a few more centuries, they were to turn their faces from the glory they won and build a wall against the universe: khedron ran the monitor backward and forward a dozen times through the brief period of history that had wroug the transformation. The change from a small open city to a much larger close one had taken little more than a thousand years. In that time, the machines that had served diaspar so faithfully must have been designed and built, and the knowl•edge that would enable them to carry out their tasks had been fed into their memory circuits. Into the memory circuits, also, must have gone th essential patterns of all the men who were now alive, so that when the righ impulse called them forth again they could be clothed in matter and would emerge re•born from the hall of creation. In some sense, alvin realized, he must have existed in that ancient world. It was possible, of course, that he was completely synthetic-that his entire per•sonality had been designed by
artist-technicians who had worked with tools of inconceivable complexity
toward some clearly envisaged goal. Yet he thought it more likely that he wa a composite of men who had once lived and walked on earth. Very little of old diaspar had remained when the new city was created; the park had obliterated it almost complete•ly. Even before the transformation, there had
been a small, grass-covered clearing at the center of diaspar, surrounding the junction of all the radial streets. Afterward it had expanded tenfold, wiping out streets and buildings alike. The tomb of yarlan zey had been brought int existence at this time, re•placing a very large circular structure which had previously stood at the meeting point of all the streets. Alvin had never really believed the legends of the tomb's antiquity, but now it seemed that they were true. "I suppose," said alvin, struck by a sudden thought, "that w can explore this image, just as we explored the image of today's diaspar?" khedron's fingers flickered over the monitor control board, and the screen answered alvin's question. The long-vanished city began to expand before his eyes as his viewpoint moved along the curiously narrow streets. This memory o the dias•par that once had been was still as sharp and clear as the image the city he lived in today. For a billion years, the informa•tion circuits h held it in ghostly pseudo-existence, waiting for the moment when someone
should call it forth again. And it was not, thought alvin, merely a memory was seeing now. It was something more complex than that-it was the memory of memory. He did not know what he could learn from it, and whether it could him in his quest. No matter; it was fascinating to look into the past and

see a world that had existed in the days when men still roamed among the stars. He pointed to the low, circular building that stood at the city's heart. "Let's start there," he told khedron. "That seems as good a place as any to begin." perhaps it was sheer luck; perhaps it was some ancient memory perhaps it was elementary logic. It made no dif. Ference since he would have arrived at this spot sooner or later-this spot upon which all the radial streets of the city converged. It took him ten minutes to discover that they did not meet here for reasons of symmetry alone ten minutes to know that hi long search had met its reward. Nine Alystra had found it very easy to follow alvin and khed•ron without their knowledge. They seemed in a great hurry•something which in itself was most unusual-and never looked back. It had been an amusing game to pursue them along the moving ways, hiding in the crowds yet always keeping them in sight. Toward the end their goal had been obvious; when they left the pattern of streets and went into the park, they could only be heading for the tomb of yarlan zey. The park con•tained no ot buildings, and people in such eager haste as alvin and khedron would not be interested merely in enjoy•ing the scenery. Because there was no way of concealing herself on the last few hundred yards to the tomb, alystra waited until khedron and alvin had disappeared into the marbled gloom. Then, as soon as they were out of sight, she hurried up the grass-cov•ered slope. She felt fairly sure that she could hide behind one of the great pillars long enough discover what alvin and khedron were doing; it did not matter if they detect her after that. The tomb consisted of two concentric rings of columns, enclosing a circular courtyard. Except in one sector, the col•umns screened
off the interior completely, and alystra avoided approaching through this opening, but entered the tomb from the side. She cautiously negotiated the first ring of columns, saw that there was no one in sight, and tiptoed acro to the second. Through the gaps, she could see yarlan zey looking` out throu the entrance, across the park he had built, and beyond that to the city ove which he had watched for so many ages. And there was no one else in all t marble solitude. The tomb was empty. At that moment, alvin and khedron were hundred feet underground, in a small, boxlike room whose walls seemed to be flowing steadily upward. That was the only indication of movement; there was
no trace of vibration to show that they were sinking swiftly into the earth, descending toward a goal that even now neither of them fully understood. It had been absurdly easy, for the way had been prepared for them. (By whom? Wondered alvin. By the central com•puter? Or by yarlan zey himself, when he transformed the city?) the monitor screen had shown them the long, vertical shaft plunging into the depths, but they had followed its course only a litt way when the image had blanked out. That meant, alvin knew, that they were asking for information that the monitor did not possess, and perhaps never ha possessed. He had scarcely framed this thought when the screen came to life once more. On it appeared a brief message, printed in the simplified script that machines had used to communicate with men ever since they had achieved intellectual equality: Stand where the statue gazes-and remember: diaspar was not always thus The last five words were in larger type, and the meaning the entire message was obvious to alvin at once. Mentally framed code message had been used for ages to unlock doors or set machines in action. As for "stand where the statue gazes"-that was really too simple. "I wonder how many people have read this message?" said alvin thoughtfully. "Fourteen, to my knowledge," replied khedron. "And there may have been others." he did not amplify this rather cryptic remark, and alvin was in too great a hurry to reach the park to question him further. They could not be certain that the mechanisms would still respond to the triggering impulse. When they reached
the tomb, it had taken them only a moment to locate the single slab among those paving the floor, upon which the gaze of yarlan zey was fixed. It was only at first sight that the statue seemed to be looking out across the cit if one stood directly in front of it, one could see that the eyes were down•cast and that the elusive smile was directed toward a spot just inside the entrance to the tomb. Once the secret was realized, there could be no

doubt about it. Alvin moved to -the next slab, and found that yarlan zey wa no longer look•ing toward him. He rejoined khedron, and mentally echoed the words that the jester spoke aloud: "diaspar was not always thus." in•stantly, as if the millions of years that had lapsed since their last operation had never existed, the waiting machines re•sponded. The great slab of stone on which they were standing began to carry them smoothly into the depths. Overhead, the patch of blue suddenly flickered out of exis•tence. The shaft
was no longer open; there was no danger that anyone should accidentally stumble into it. Alvin wondered fleetingly if another slab of stone had somehow been materi•alized to replace the one now supporting him and khedron,
then decided against it. The original slab probably still paved the tomb; the one upon which they were standing might only exist for infinitesimal fractions of a second, being continuous•ly re-created at greater and greater depths in the earth to give the illusion of steady downward movement. Neither alvin nor khedron spoke as the walls flowed silent•ly past them. Khedron was once again wrestling with his con•science, wondering if this time he had gone too far. could not imagine where this route might lead, if indeed it led any•where. F the first time in his life, he began to understand the real meaning of fear Alvin was not afraid; he was too excited. This was the sensation he had kno in the tower of loranne, when he had looked out across the untrodden desert and seen the stars conquering the night sky. He had merely gazed at the iu•known then; he was being carried toward it now. The walls ceased to flow past them. A patch of light ap•peared at one side of their mysteriously movi room, grew brighter and brighter, and was suddenly a door. They stepped
through it, took a few paces along the short corridor beyond -and then were standing in a great, circular cavern whose walls came together in a sweeping curve three hundred feet above their heads. The column down whose interior
they had descended seemed far too slim to support the millions of tons of r above it; indeed, it did not seem to be an integral part of the chamber at all, but gave the impression of being an after•thought. Khedron, following alvin's gaze, arrived at the same conclusion. "This column," he said, speaking rather jerkily, as if anx•ious to find something to say, "was built simply t house the shaft down which we came. It could never have carried the traffic that must have passed through here when diaspar was still open to the world. That came through those tunnels over there; i suppose you recognize what they are?" alvin looked toward the walls of the chamber, more than a hundred yard away. Piercing them at regular intervals were large tunnels, twelve of them, radiating in all directions exact•ly as the moving ways still did today. He could see that they sloped gently upward, and now he recognized the familiar gray surface of the moving ways. These were only the severed stumps of the great roads; the strange material that gave them life was now frozen into immobility. When the park had been built, the hub of the moving way system been buried. But it had never been destroyed. Alvin began to walk toward the nearest of the tunnels. He had gone only a few paces when he realized that something was happening to the ground beneath his feet. It was becom•ing transparent. A few more yards, and he seemed to be stand•ing in midair witho visible support. He stopped and stared down into the void beneath him. "Khedron!" he called. "Come and look at this!" the other joined him, and together they gazed at the marvel beneath their feet. Faintly visible, at an indefinite depth, lay an enormous map--a great network of lines converging to•ward a spot beneath the central shaft. They stared at it in silence for moment; then khedron said quietly: you realize what this is?" "i think so," replied alvin. "It's a map of the entire trans•port system, and those little circles must be the other cities of earth. I can just see names beside them but they're too faint to read." "there must have been some form of internal illumination once," said khedron absently. He was tracing the lines beneath
his feet, following them with his eyes out toward the walls of the chamber. thought so!" he exclaimed suddenly. "Do you see how these radiating lines lea toward the small tunnels?" alvin had noticed that besides the great arches of the mov•ing ways there were innumerable smaller tunnels leading out of the

chamber-tunnels that sloped downward instead of up. Kedron continued without waiting for a reply. Ht would be hard to think of a simpler system. People would come down the moving ways, select the place they wished to visit, and then follow the appropriate line on the map. "And what happened to them afte that?" asked alvin. Khedron was silent, his eyes searching out the mystery of those descending tunnels. There were thirty or forty of them, all looking exactly the same. Only the names on the map would have enabled one to distinguish between them, and those names were indecipherable now. Alvin had wandered away and was circumnavigating the central pillar. Presently his voice came to khedron, slightly muffled and overlaid with echoes from the walls of the cham•ber. "What is it?' called khedron, not wishing to move, be•cause he had nearly succeeded in reading one of the dimly visible groups of characters But alvin's voice was insistent, so he went to join him. Far beneath was th other half of the great map, its faint webwork radiating to the points of t compass. This time, however, not all of it was too dim to be clearly seen, one of the lines and only one-was brilliantly illuminated. It seemed to have no connection with the rest of the system, and pointed like a gleaming arrow to one of the downward-slop•ing tunnels. Near its end the line transfixed a circle of golden light, and against that circle was the single word lys. Tha was all. For a long time alvin and khedron stood gazing down at that silent symbol. To khedron it was a challenge he knew he could never accept-and whic indeed, he would rather did not exist. But to alvin it hinted at the fulfillment of all his dreams; though the word lys meant nothing to him, he let it roll around his mouth, tasting its sibilance like some exotic flavor. The blood was pounding in his veins, and his cheeks were flushed as by a fever. He stared around this great con•course, trying to imagine it as it ha been in the ancient days, when air transport had come to an end but the ci of earth still had contact with one another. He thought of the countless millions of years that had passed with the traffic steadily dwindling and the lights on the great map dying one by one, until at last only this single l remained. How long, he wondered, had it gleamed there among its darkened companions, waiting to guide the steps that never came, until yarlan zey had sealed the moving ways and closed diaspar against the world? And that had be a billion years ago. Even then, lys must have lost touch with diaspar. It seemed impossible that it could have survived; perhaps, after all, the map meant nothing now. Khedron broke into his reverie at last. He seemed nerv•ous and ill at ease, not at all like the confident and self-as•sured person that he had always been in the city above. "I do not think that we should go a farther now," he said. "`It may not be safe until-until we are more pre•pared." there was wisdom in this, but alvin recognized the un•derlying
note of fear in khedron's voice. Had it not been for that, he might have b sensible, but a too-acute awareness of his own valor, combined with a contemp for khedron's timidity, drove alvin onward. It seemed foolish to have come so far, only to turn back when the goal might be in sight. "I'm going down th tunnel," he said stubbornly, as if challenging khedron to stop him. "I want see where it leads." he set off resolutely, and after a moment's hesita•tion the jester followed him along the arrow of light that burned beneath their feet. As they stepped into the tunnel, they felt the familiar tug of the peristaltic field, and in a moment were being swept effortlessly into the depths. The journey lasted scarcely a minute; when the field released them
they were standing at one end of a long narrow chamber in the form of a half•cylinder. At its distant end, two dimly lit tunnels stretched away toward infinity. Men of almost every civilization that had existed since the dawn would have found their surroundings completely famil•iar, yet to alvin and khedron this was a glimpse of another world. The purpose of the long, streamlined machine that lay aimed like a projectile at the far tunnel was obvious, but that made it none the less novel. Its upper portion was transparent, and looking through the walls alvin could see rows of luxuriously appointed seats. There was no sign of any entrance, and the entire machine w floating about a foot above a single metal rod that stretched away into the

distance, disappearing in one of the tunnels. A few yards away another rod l to the second tunnel, but no machine floated above it. Alvin knew, as surely as if he had been told, that somewhere beneath unknown, far-off lys, that second machine was waiting in another such chamber as this. Khedron began to talk, a little too swiftly. "What a peculiar transport system! It could only handle a hundred people at a time, so they could not have expected much traffic. And why did they go to all this trouble to bury themselves in the earth if the skies were still open? Perhaps the invaders would not even perm them to fly, though i find that hard to believe. Or was this built during transi•tion period, while men still traveled but did not wish to be reminded of space? They could go from city to city, and never see the sky and the stars." he gave a nervous laugh. "I feel sure of one thing, alvin. When lys existed, it was much like diaspar. All cities must be essentially the same. wonder that they were all abandoned in the end, and merged into diaspar. Wha was the point of having more than one?" alvin scarcely heard him. He was bu examining the long projectile trying to find the entrance. If the machine was controlled by some cental or verbal code order, he might never be able to m it obey him, and it would remain a maddening enigma for the rest of his li The silently opening door took him completely unawares. There was no sound, n warning when a section of the wall simply faded from sight and the beautiful designed interior lay open before his eyes. This was the moment of choice. Until this instant, he had always been able to turn back if he wished. But he stepped inside that welcoming door, he knew what would happen, though not where it would lead. He would no longer be in control of his own destiny, would have placed himself in the keeping of unknown forces. He scarcely hesitated. He was afraid to hold back, being fearful that if he waited too long this moment might never come again-or that if it did, his courage might not match his desire for knowledge. Khedron opened his mouth in anx•ious protest, but before he could speak, alvin had stepped through the entrance. H turned to face khedron, who was standing framed in the barely visible
rectangle of the door•way, and for a moment there was a strained silence whi each waited for the other to speak. The decision was made for them. There w a faint flicker of translucence, and the wall of the machine had closed agai Even as alvin raised his hand in farewell, the long cylinder started to ease itself forward. Before it had entered the tun•nel, it was already moving
faster than a man could run. There had been a time when, every day, million of men made such journeys, in machines basically the same as this, as they shuttled between their homes and their humdrum jobs. Since that far-off day, man had explored the universe and returned again to earth-had won an empire, and had it wrestled from his grasp. Now such a journey was being made again in a machine wherein legions of forgotten and unadventurous men would have
felt completely at home. And it was to be the most momentous journey any hu being had undertaken for a billion years. Alystra had searched the tomb a dozen times, though once was quite sufficient, for there was nowhere anyone could hide. After the first shock of surprise, she had wondered if what she had followed across the park had not been alvin and khedron at all, but onl their projections. But that made no sense; projections were materialized at
any spot one wished to visit, without the trouble of going there in person. sane person would "walk" his projected image a couple of miles, taking half hour to reach his destination, when he could be there instantly. No; it was the real alvin and the real khedron that she had followed into the tomb. Somewhere, then, there must be a secret entrance. She might as well look for it while she was waiting for them to come back. As luck would have it, she missed khedron's reappearance, for she was examining a column behind the
statue when he emerged on the other side of it. She heard his footsteps, turned toward him, and saw at once that he was alone. "Where is alvin?" she cried. It was some time before the jester answered. He looked distraught and irresolute, and alystra had to repeat her ques•tion before he took any notice of her. He did not seem in the least surprised to find her there. "I do n know where he is," he answered at last. "I can only tell you that he is o

way to lys. Now you know as much as i do." it was never wise to take khe words at their face value. But alystra needed no further assurance that the jes•ter was not playing his role today. He was telling her the truth-whatever it might mean. Ten When the door closed behind him, alvin slumped into t nearest seat. All strength seemed suddenly to have been drained from his legs at last he knew, as he had never known before, that fear of the unknown th haunted all his fellow men. He felt himself trembling in every limb, and his sight became misty and uncertain. Could he have escaped from this speeding machine he would willingly have done so, even at the price of abandoning all his dreams. It was not fear alone that overwhelmed him, but a sense of unutterable loneliness. All that he knew and loved was in diaspar; even if h was going into no danger, he might never see his world again. He knew, as man had known for ages, what it meant to leave one's home forever. In this moment of desolation, it seemed to him of no importance whether the path he was following led to peril or to safety; all that mattered to him now was
it led away from home. The mood slowly passed; the dark shadows lifted from his mind. He began to pay attention to his surroundings, and to see what he could learn from the unbelievably ancient ve•hicle in which he was traveling. It did not strike alvin as particularly strange or marvelous that this buried transport system should still function perfectly after such aeons of time. It was not preserved in the eternity circuits of the city's own monitors, but there must be similar circuits elsewhere guarding it from change or decay. Fo the first time he noticed the indicator board that formed part of the forwar wall. It carried a brief but reassuring message: lys 35 minutes Even as he watched, the number changed to " 34." that at least was useful information, though since he had no idea of the machine's speed it told him nothing abou the length of the journey. The walls of the tunnel were one continual blur gray, and the only sensation of movement was a very slight vibration he woul never have noticed had he not looked for it. Diaspar must be many miles awa by now, and above him would be the desert with its shifting sand dunes. Per•haps at this very moment he was racing below the broken hills he had watched so often from the tower of loranne. His imagination sped onward to lys, as if impatient to arrive ahead of his body. What sort of a city woul be? No matter how hard he tried, he could only picture another and smaller version of diaspar. He wondered if it still existed, then assured himself tha not otherwise would this machine be carrying him swiftly through the earth. Suddenly there was a distinct change in the vibration under•foot. The vehicle was slowing down-there was no question of that. The time must have passed mo swiftly than he had thought; somewhat surprised, alvin glanced at the
indicator. Lys 23 minutes Feeling puzzled, and a little worried, he pressed his face against the side of the machine. His speed was still blurring the walls of the tunnel into a featureless gray, yet now from time to time he could catch a glimpse of markings that disap•peared almost as quickly as they came. And at each disap•pearance, they seemed to remain in his field of visi for a little longer. Then, without any warning, the walls of the tunnel were snatched away on either side. The machine was passing, still at a very great speed, through an enormous empty space, far larger even than the chamber of the moving ways. Peering in wonder through the transparent walls, alvin could glimpse beneath him an intricate network of guiding rods, rods that crossed
and crisscrossed to disappear into a maze of tunnels on either side. A flood of bluish light poured down from the arched dome of the ceiling and silhouetted against the glare he could just make out the frameworks of great machines. The light was so brilliant that it pained the eyes, and alvin knew that this place had not been intended for man. A moment later, his vehicle flashed past row after row of cylinders, lying motionless above their guide rails. They were much larger than the one in which he was traveling, and al guessed that they must have been used for transporting freight. Around them were grouped incomprehensible, many-•jointed mechanisms, all silent and
stilled. Almost as quickly as it had appeared, the vast and lonely chamber vanished behind him. Its passing left a feeling of awe in alvin's mind; for

the first time he really understood the meaning of that great, darkened map below diaspar. The world was more full of wonder than he had ever dreamed. Alvin glanced again at the indicator. It had not changed; he had taken less than a minute to flash through the great cavern. The machine was accelerating again; though there was little sense of motion, the tunnel walls were flowing past on either side at a speed he could not even guess. It seemed an age before that indefinable change of vibra•tion occurred again. Now the indicator was reading: Lys 1 minute That minute was the longest that alvin had eve known. More and more slowly moved the machine; this was no mere slackening o its speed. It was coming at last to rest. Smoothly and silently the long cylinder slid out of the tunnel into a cavern that might have been the twin the one below diaspar. For a moment alvin was too excited to see anything clearly; the door had been open for a considerable time before he realized that he could leave the vehicle. As he hurried out of the machine, he caugh last glimpse of the indicator. Its wording had now changed and its message w infinitely reassuring: Diaspar 35 minutes As he began to search for a way out of the chamber, alvin found the first hint that he might be in a civilization dif•ferent from his own. The way to the surface clearly lay through a low, wide tunnel at one end of the cavern-and leading up through tunnel was a flight of steps. Such a thing was extremely rare in diaspar; t architects of the city had built ramps or sloping corridors whenever there wa a change of level. This was a survival from the days when most robots had moved on wheels, and so found steps an impassable barrier. The stairway was very short, and ended against doors that opened automatically at alvin's approach. He walked into a small room like that which had carried him down shaft under the tomb of yarlan zey, and was not surprised when a few minute later the doors opened again to reveal a vaulted corridor rising slowly to a archway that framed a semicircle of sky. There had been no sensation of movement, but alvin knew that he must have risen many hundreds of feet. He hurried forward up the slope to the sunlit opening, all fear forgotten in hi eagerness to see what lay before him. He was standing at the brow of a low hill, and for an in•stant it seemed as if he were once again in he central park of diaspar. Yet if this were indeed a park, it was too enormous for h mind to grasp. The city he had expected to see was nowhere visible. As far the eye could reach there was nothing but forest and grass-covered plains.
Then alvin lifted his eyes to the horizon, and there above the trees, sweepi fiom right to left in a great arc that encircled the world, was a line of stone which would have dwarfed the mightiest giants of diaspar. It was so fa away that its details were blurred by sheer distance, but there was something about its outlines that alvin found puzzling. Then his eyes became at last accustomed to the scale of that colos•sal landscape, and he knew that those far-off walls had not been built by man. Time had not conquered everything earth still possessed mountains of which she could be proud. For a long time alvin stood at the mouth of the tunnel, slowly growing accustomed to the strange world in which he had found himself. He was half stunned by the imp of sheer size and space; that ring of misty mountains could have enclosed a dozen cities as large as diaspar. Search as he might, however, alvin could s no trace of human life. Yet the road that led down the hillside seemed
well-kept; he could do no better than accept its guidance. At the foot of t hill, the road disappeared between great trees that almost hid the sun. As alvin walked into their shadow, a strange medley of scents and sounds greeted him. The rustle of the wind among the leaves he had known be•fore, but underlying that were a thousand vague noises that conveyed nothing to his
mind. Unknown odors assailed him, smells that had been lost even to the memo of his race. The warmth, the profusion of scent and color, and the unseen presences of a million living things, smote him with almost physical violence. He came upon the lake without any warning. The trees to the right suddenly ended, and before him was a great expanse of water, dotted with tiny islands Never in his life had alvin seen so much water; by comparison, the largest pools in diaspar were scarcely more than puddles. He walked slowly down to t

edge of the lake and cupped the warm water in his hands, letting it trickle through his fingers. The great silver fish that suddenly forced its way
through the underwater reeds was the first nonhuman creature that alvin had ever seen. It should have been utterly strange to him, yet its shape teased his mind with a haunting familiarity. As it hung there in the pale green vo its fins a faint blur of motion, it seemed the very embodiment of power and speed. Here, incorporated in living flesh, were the graceful lines of the
great ships that had once ruled the skies of earth. Evolution and science ha come to the same answers; and the work of nature had lasted longer. At last alvin broke the lake's enchantment, and continued along the winding road. The forest closed around him once more, but only for a little while. Presently t road ended, in a great clearing half a mile wide and twice as long-and alvi understood why he had seen no trace of man before. The clearing was full low, two-storied buildings, colored in soft shades that rested the eye even i the full glare of the sun. Most were of clean, straightforward design, but several were built in a complex architectural style involving the use of
fluted columns and gracefully fretted stone. In these buildings, which seemed of great age, the immeasurably an•cient device of the pointed arch was used. As he walked slowly toward the village, alvin was still struggling to grasp his new surroundings. Nothing was famil•iar; even the air had changed, with its hint of throbbing, unknown life. And the tall, golden-haired people going among the buildings with such unconscious grace were obviously of a different stock from the men of diaspar. They took no notice of alvin, and that was strange, for his clothing was totally different from theirs. Since the tem•perature never changed in diaspar, dress there was purely ornamental and often extremely elaborate. Here it seemed mainly functional, designed for use rather than display, and frequently consisted of a single sheet draped around
the body. It was not until alvin was well inside the. Village that the peop of lys reacted to his presence, and then their re•sponse took a somewhat unexpected form. A group of five men emerged from one of the houses and beg to walk purposefully toward him-almost as if, indeed, they had been expecting his arrival. Alvin felt a sudden, heady ex•citement, and the blood pounded in his veins. He thought of all the fateful meetings men must have had with ot races on far-off worlds. Those he was meeting now were of his own species-bu how had they diverged in the aeons that had sundered them from diaspar? The delegation came to a halt a few feet away from alvin. Its leader smiled, holding out his hand in the ancient ges•ture of friendship. "We thought it best to meet you here," he said. "Our home is very different from diaspar, the walk from the ter•minus gives visitors a chance to become acclimatized." alvin accepted the outstretched hand, but for a moment was too surprised to reply. Now he understood why all the other villagers had ignored him so completely. "You knew i was coming?" he said at length. "Of course. We alway know when the carriers start to move. Tell me-how did you discover the way? has been such a long time since the last visitor that we feared the se•cret had been lost." the speaker was interrupted by one of his companions. "I thi we'd better restrain our curiosity, gerane. Seranis is waiting." the name "seranis" was preceded by a word unfamiliar to alvin, and he assumed that it was a title of some kind. He had no difficulty in understanding the others, and it never occurred to him that there was anything surprising about this. Diaspar and lys shared the same linguistic herit•age, and the ancient
invention of sound recording had long ago frozen speech in an unbreakable mold. Gerane gave a shrug of mock resignation. "Very well," he smiled.
"Seranis has few privileges-i should not rob her of this one." as they walke deeper into the village, alvin studied the men around him. Thev appeared
kindly and intelligent, but these were virtues he had taken for granted all his life, and he was looking for ways in which they differed from a similar group in diaspar. There were differences, but it was hard to define them. Th were all somewhat taller than alvin, and two of them showed the unmistakable marks of physical age. Their skins were very brown, and in all their movemen they seemed to radiate a vigor and zest which alvin found refreshing, though

at the same time a little bewildering. He smiled as he remembered khedron's proph•ecy that, if he ever reached lys, he would find it exactly the same a diaspar. The people of the village now watched with frank curi•osity as alvin followed his guides; there was no longer any pretense that they took him for granted. Suddenly there were shrill, high-pitched shouts from the trees on the right, and a group of small, excited creatures burst out of the woods and crowded around alvin. He stopped in utter amazement, unable to believe his eyes. Here was something that his world had lost so long ago that it lay i the realms of mythology. This was the way that life had once begun; these noisy, fascinating creatures were human children. Alvin watched them with wondering disbelief-and with another sensation which tugged at his heart but which he could not yet identify. No other sight could have brought home to
so vividly his remoteness from the world he knew. Diaspar had paid, and paid in full, the price of immor•tality. The party halted before the largest building alvin had yet seen. It stood in the center of the village and from flagpole on its small circular tower a green pennant floated along the breeze All but gerane dropped behind as he entered the build•ing. Inside it was qui and cool; sunlight filtering through the translucent walls fit up everything with a soft, restful glow. The floor was smooth and resilient, inlaid with fine mosaics. On the walls, an artist of great ability and power had depicte a set of forest scenes. Mingled with these paintings were other murals which conveyed nothing to alvin's mind, yet which were attractive and pleasant to look upon. Let into one wall was a rectangular screen filled with a shifting maze of colors•presumably a visiphone receiver, though a rather small one.
They walked together up a short circular stairway that led them out onto the flat roof of the building. From this point the entire village was visible, a alvin could see that it con•sisted of about a hundred buildings. In the distance the trees opened out to enclose wide meadows, where animals of sev•eral different types were grazing. Alvin could not imagine what these
were, most of them were quadrupeds, but some seemed to have six or even eig legs. Seranis was waiting for him in the shadow of the tower, alvin wondered how old she was; her long, golden hair was touched with gray, which he gues must be some indica•tion of age. The presence of children, with all the consequences that implied, had left him very confused. Where there was birth, then surely there must also be death, and the life span here in lys might very different from that in diaspar. He could not tell whether seranis was fifty, five hundred, or five thousand years old, but looking into her eyes b could sense that wisdom and depth of experience be sometimes felt when he wa with jeserac. She pointed to a small seat, but though her eyes smiled a welcome she said nothing until alvin had made himself com•fortable-or as comfortable as he could be under that in•tense though friendly scrutiny. The she sighed, and addressed alvin in a low gentle voice. "This is an occasion which does not often arise, so you will excuse me if i do not know the co behavior. But there are certain rights due to a guest, even if an unexpected one. Before we talk, there is something about which i should warn you. I ca read your mind." she smiled at alvin's obvious consternation, and added
quickly: "there is no need to let that worry you. No right is respected mor strongly than that of mental privacy. I will enter your mind only if you invite me to. But it would not be fair to hide this fact from you, and it explain why we find speech somewhat slow and difficult. It is not often used here." this revelation, though slightly alarming, did not surprise alvin. Once both men and machines had possessed this power, and the unchanging machines could still read their masters' orders. But in diaspar, man himself had lost the gift he had once shared with his slaves. "I do not know what brought y from your world to ours," continued seranis, "but if you are looking for lif your search has ended. Apart from diaspar, there is only des•ert beyond our mountains." it was strange that alvin, who had questioned accepted be•liefs so often before, did not doubt the words of seranis. His only reaction was one sadness that all his teaching had been so nearly true. "Tell me about lys," begged. "Why have you been cut off from diaspar for so long, when you seem

know so much about us?" seranis smiled at his eagerness. "Presently," she
said. "But first i would like to know some•thing about you. Tell me how you found the way here, and why you came. " Haltingly at first, and then with growing confidence. Alvin told his story. He had never spoken with such
freedom be•fore; here at last was someone who would not laugh at his dreams because they knew those dreams were true. Once or twice seranis interrupted him with swift questions, when he mentioned some aspect of diaspar that was unfamiliar to her. It was hard for alvin to realize that things which were
part of his everyday life would be meaningless to someone who had never live in the city and knew nothing of its complex cul•ture and social organization. Seranis listened with such under•standing that he took her comprehension for granted; not until much later did he realize that many other minds besides hers were listening to his words. When he had finished, there was silence fo a while. Then seranis looked at him and said quietly: "why did you come to lys?" alvin glanced at her in surprise "i've told you," he said. ` I wanted explore the world. Everyone told me that there was only desert beyond the city, but i had to see for myself." "and was that the only reason?" alvin hesitated. When at last he answered, it was not the indomitable explorer who spoke, but the lost child who had been born into an alien world "no," he s softly, "that wasn't the only reason-though i did not know it until now i w lonely " "lonely? In diaspar?" there was a smile on the lips of seranis, bu sympathy in her eyes, and alvin knew that she expected no further answer. No that he had told his story, he waited for her to keep her share of the bargain. Presenty seranis rose to her feet and began to pace to and fro on roof. "I know the questions you wish to ask," she said. "Some of them i ca answer, but it would be wearisome to do it in words. If you will open your mind to me, i will tell you what you need to know. You can trust me: i w take nothing from you without your permission." "what do you want me to do?" said alvin cautiously. "Will yourself to accept my help-look at my eyes-and forget everything," commanded seranis. Alvin was never sure what happened
then. There was a total eclipse of all his senses, and though he could neve remember acquiring it, when he looked into his mind the knowledge was there. He saw back into the past, not clearly, but as a man on some high mountain might look out across a misty plain. He understood that man had not always been a city dweller, and that since the machines gave him freedom from toil there had always been a rivalry between two different types of civilizaton. I the dawn ages there had been thousands of cities, but a large part of manki had preferred to live in relatively small communities. Universal transport and instan•taneous communication had given them all the contact they required with the rest of the world, and they felt no need to live huddled together with millions of their fellows. Lys had been little different, in the early days, from hun•dreds of other communities. But gradually, over the ages, it
developed an independent culture which was one of the highest that mankind ha ever known. It was a culture based largely upon the direct use of mental power, and this set it apart from the rest of human society, which came to rely more and more upon machines. Through the aeons, as they advanced along their different roads, the gulf between lys and the cities widened. It was bridged only in times of great crisis; when the moon was falling its destruction was carried out by the scientists of lys. So also was the defens of earth against the invaders, who were held at bay in the final battle of shalmirane. That great ordeal exhausted mankind; one by one the cities died
and the desert rolled over them. As the population fell, humanity began the migration that was to make diaspar the last and greatest of all cities. Most of these changes did not affect lys, but it had its own battle to fight-the battle against the desert. The natural barrier of the mountains was not
enough, and many ages passed before the great oasis was made secure. The picture was blurred here, perhaps deliberately. Alvin could not see what had been done to give lys the virtual eternity that di•aspar had achieved. The voice of seranis seemed to come to him from a great distance-yet it was not her voice alone, for it was merged into a symphony of words, as though many

other tongues were chanting in unison with hers. "That, very briefly, is our history. You will see that even in the dawn ages we had little to do with cities, though their people often came into our land. We never hindered them, for many of our greatest men came from outside, but when the cities were dy we did not wish to be involved in their downfall. With the ending of air transport there was only one way into lys-the carrier system from diaspar. It was closed at your end, when the park was built-and you forgot us, though w have never forgotten you. "Diaspar has surprised us. We expected it to go th way of all other cities, but instead it has achieved a stable cul•ture that may last as long as earth. It is not a culture that we admire yet we are that those who wish to escape have been able to do so. More than you might think have made the journey, and they have almost always been outstanding men who brought something of value with them when they came to lys." the voice faded; the paralysis of alvin's senses ebbed away and he was himself again. saw with astonishment that the sun had fallen far below the trees and that eastern sky already held a hint of night. Somewhere a great bell vibrated wi a throbbing boom that pulsed slowly into silence, leaving the air tense with mystery and premonition. Alvin found him•self trembling slightly, not with the first touch of the evening's chill, but through sheer awe and wonder at all that he had learned. It was very late, and he was far from home. He had a sudden need to see his friends again, and to be among the familiar sights a scenes of diaspar. "I must return," he said. "Khedron-my parents-they will be expecting me." that was not wholly true; khedron would certainly be won•dering what had happened to him, but as far as alvin was aware no one else knew
he had left diaspar. He could not have explained the reason for this mild deceit, and was slightly ashamed of himself as soon as he had uttered the words. Seranis looked at him thoughtfully. "I am afraid it is not as easy a that," she said. "What do you mean?" asked alvin. "Won't the carrier that brought me here take me back again?" he still refused to face the idea that might be held in lys against his will, though the idea had briefly crossed mind. For the first time, seranis seemed slightly ill at ease. "We have been talking about you," she said-not explain•ing who the "we" might be, nor
exactly how they had con- sulted together. "If you return to diaspar, the whole city will know about us. Even if you promise to say nothing, you woul find it impossible to keep our secret." "why should you wish it kept?" asked alvin. "Surely it would be a good thing for both our peoples if they could meet again." seranis looked displeased. "We do not think so," she said. "If the gates were opened, our land would be flooded with the idly curious and sensa•tion seekers. As it is now, only the best of your people have ever reached us." this reply radiated so much unconscious superiority, yet was
based on such false assumptions, that alvin felt his annoyance quite eclipse his alarm. "That isn't true," he said flatly. "I do not believe you would f another person in diaspar who could leave the city, even if he wanted to-eve if he knew that there was somewhere to go. If you let me return, it would no difference to lys." "it is not my decision," explained seranis, "and you under•estimate the powers of the mind if you think that the barriers that ke your people inside their city can never be broken. However, we do not wish hold you here against your will, but if you return to diaspar we must erase all memories of lys from your mind." she hesitated for a moment. "This has never risen before; all your predecessors came here to stay." here was a choice that alvin refused to accept. He wanted to explore lys, to learn all its secrets, to discover the ways in which it differed from his own home, b equally he was determined to return to diaspar, so that he could prove to h friends that he had been no idle dreamer. He could not understand the reason prompting this desire for secrecy; even if he had, it would not have made a difference in his be•havior. He realized that he must play for time or else convince seranis that what she asked him was impossible. "Khedron knows where
i am," he said. "You cannot erase his memories." seranis smiled. It was a pleasant smile, and one that in any other circumstances would have been friendly enough. But behind it alvin glimpsed, for the first time, the

presence of overwhelming and implacable power. "You underestimate us, alvin,"
she replied. "That would be very easy. I can reach diaspar more quickly than can cross lys. Other men have come here before, and some of them told their friends where they were going. Yet those friends forgot them, and they
vanished from the history of diaspar." alvin had been foolish to ignore this possibility, though it was obvious, now that seranis had pointed it out. He won•dered how many times, in the millions of years since the two cultures we separated, men from lys had gone into di•aspar in order to preserve their jealously guarded secret. And he wondered just how extensive were the mental powers which these strange people. Possessed and did not hesitate to use. Was it safe to make any plans at all? Seranis had promised that she would not his mind without his consent, but he wondered if there might be circumstances in which that promise would not be kept. "Surely," he said, "you don't expec me to make the deci•sion at once. Cannot i see something of your country before i make my choice?" "of course," replied seranis. "You can stay here a long as you wish, and still return to diaspar eventually if you change your mind. But if you can decide within the nekt few days, it will be very much easier. You do not want your friends to be worried, and the longer you are missing the harder it will be for us to make the necessary adjustments." alv could appreciate that; he would like to know just what those "adjustments" were. Presumably someone from lys would contact khedron-without the jester
ever being aware of it-and tamper with his mind. The fact of alvins disappearance could not be concealed, but the information that he and khedron had discovered could be obliterated. As the ages passed, alvin's name would join those of the other uniques who had mysteriously vanished without trace and had then been forgotten. There were many mysteries here, and he seemed no closer to solving any of them. Was there any purpose behind the curious, one-sided relationship between lys and diaspar, or was it merely a historical accident? Who and what were the uniques, and if the people from l could enter diaspar, why had they not canceled the memory circuits that held the clue to their existence? Perhaps that was the only ques•tion to which alvin could give a plausible answer. The cen•tral computer might be too stubborn an opponent to tackle, and would hardly be affected by even the mos advanced of mental techniques. He put these problems aside; one day, when he had learned a great deal more, he might have some chance of answering them. was idle to speculate, to build pyramids of surmise on a foundation of ignorance. "Very well," he said, though not too graciously, for he was still annoyed that this unexpected obstacle had been placed in his path. "I'll give you my answer as soon as i can, if you will show me what your land is li "good," said seranis, and this time her smile held no hidden threat. "We are proud of lys, and it will be a pleas•ure to show you how men can live wit the aid of cities. Meanwhile, there is no need for you to worry-your friends will not be alarmed by your absence. We shall see to that, if only for our protection." it was the first time seranis had ever made a promise that she could not keep. Eleven Try as she would, alystra could extract no further infor• mation from khedron. The jester had recovered quickly from his initial shock, and from the panic that had sent him flying back to the surface when found himself alone in the depths beneath the tomb. He also felt ashamed of his cowardly be•havior, and wondered if he would ever have the courage to return to the chamber of the moving ways and the network of world-ranging tunnels that radiated from it. Although he felt that alvin had been impatient if not indeed foolhardy, he did not really believe that he would run into a danger. He would return in his own good time. Khedron was certain of that. Well, almost certain; there was just enough doubt to make him feel the need for caution. It would be wise, he decided, to say as little as possible for the time being, and to pass the whole thing off as another joke. Unfortunate for this plan, he had not been able to mask his emotions when alystra encountered him on his return to the surface. She had seen the fear written
had at once interpreted it as meaning that alv reassurances were in vain, and she became more

and more angry with him as they walked together back through the park. At first alystra had wanted to remain at the tomb, waiting for alvin to return whatever mysterious manner he had vanished. Khed•ron had managed to convince her that this would be a waste of time, and was relieved when she followed
back to the city. There was a chance that alvin might return almost at once and he did not wish anyone else to discover the secret of yarlan zey. By t time they had reached the city, it was obvious to khedron that his evasive tactics had failed completely and the situation was seriously out of hand. It was the first time in his life that he had ever been at a loss and had n felt himself capable of dealing with any problem that arose. His immediate an irrational fear was being slowly replaced by a profounder and more firmly
based alarm. Until now, khedron had given little thought to the consequences of his actions. His own interests, and a mild but genuine em•pathy toward alvin, had been sufficient motive for all that he had done. Though he had given encouragement and as•sistance to alvin, he had never believed that anything like this could ever really happen. Despite the gulf of years and experience between them, alvin's will had always been more powerful than his own. It was too late to do anything about it now; khedron felt that events were sweeping him along toward a climax utterly beyond his control. In view this, it was a little unfair that alystra obviously regarded him as alvin's evil genius and showed an inclina•tion to blame him for all that had happene Alystra was not really vindictive, but she was annoyed, and part of her annoyance focused on khedron. If any action of hers caused him trouble, she would be the last person to be sorry. They parted in stony silence when the had reached the great circular way that surrounded the park. Khedron watched alystra disappear into the distance and wondered wearily what plans were
brewing in her mind. There was only one thing of which he could be certain now. Boredom would not be a serious problem for a considerable time to come. Alystra acted swiftly and with intelligence. She did not bother to contact eriston and etania; alvin's parents were pleasant nonentities for whom she
felt some affection but no respect. They would only waste time in futile arguments and would then do exactly as alystra was doing now. Jeserac listene to her story without apparent emotion. If he was alarmed or surprised, he concealed it well-so well that alystra was somewhat disappointed. It seemed to her that nothing so extraordinary and important as this had ever happened before, and jeserac's matter-of-fact behavior made her feel deflated. When she had finished, he questioned her at some length, and hinted, without actually saying so, that she might have made a mistake. What reason was there for sup•posing that alvin had really left the city? Perhaps it bad been a trick her expense; the fact that khedron was involved made this seem highly
probable. Alvin might be laughing at her, concealed somewhere in diaspar, at this very moment. The only positive reaction she got out of jeserac was a promise to make inquiries and to contact her again within a day. In the meantime she was not to worry, and it would also be best if she said nothi to anyone else about the whole affair. There was no need to spread alarm ov an incident that would probably be cleared up in a few hours. Alystra left jeserac in a mood of mild frustration. She would have been more satisfied could she have seen his behavior immediately after she had left. Jeserac had friends on the council; he had been a member himself in his long life, and might be again if he was unlucky. He called three of his most influential colleagues and cau•tiously aroused their interest. As alvin's tutor, he was
well aware of his own delicate position and was anxious to safe•guard himself For the present, the fewer who knew what had happened, the better. It was immediately agreed that the first thing to do was to contact khedron and ask him for an explanation. There was only one defect in the excellent plan. Khedron had anticipated it and was nowhere to be found. If there was any ambiguity about alvin's position, his hosts were very careful not to remind
him of it. He was free to go anywhere he wished in airlee, the little vill over which seranis ruled-though that was too strong a word to de•scribe her position. Sometimes it seemed to alvin that she was a benevolent dictator, bu

at others it appeared that she had no powers at all. So far he had failed completely to understand the social system of lys, either because it was too simple or else so complex that its ramifications eluded him. All he had discovered for certain was that lys was divided into innumerable villages, of which airlee was a quite typical example. Yet in a sense there were no typi examples, for alvin had been assured that every village tried to be as unlik its neighbors as possible. It was all extremely confusing. Though it was very small, and contained less than a thou•sand people, airlee was full of surprises. There was hardly a single aspect of life that did not differ from its counterpart in diaspar. The differences extended even to such
fun•damentals as speech. Only the children used their voices for normal communication; the adults scarcely ever spoke, and after a while alvin decided that they did so only out of politeness to him. It was a curiously frustrat experience to feel oneself enmeshed in a great net of soundless and un•detectable words, but after a while alvin grew accustomed to it. It seemed surprising that vocal speech had survived at all since there was no longer a use for it, but alvin later discovered that the people of lys were very fon of singing, and indeed of all forms of music. Without this incentive, it was very likely that they would long ago have become com•pletely mute. They were always busy, engaged on tasks or problems which were usually incomprehensible
to alvin. When he could understand what they were doing, much of their work seemed quite unnecessary. A considerable part of their food, for example, was actually grown, and not synthesized in accord•ance with patterns worked out
ages ago. When alvin com•mented on this it was patiently explained to him th the people of lys liked to watch things grow, to carry out com•plicated genetic experiments and to evolve ever more subtle tastes and flavors. Airlee was famous for its fruits, but when alvin ate some choice samples they seeme to him no better than those be could have conjured up in diaspar by no mor effort than raising a finger. At first he wondered if the people of lys had forgotten, or had never possessed, the powers and machines that he tookfor granted and upon which all life in diaspar was based. He soon found that th was not the case. The tools and the knowledge were there, but they were use only when it was essential. The most striking example of this was provided b the transport system, if it could be dignified by such a name. For short distances people walked, and seemed to enjoy it. If they were in a hurry, o had small loads to move, they used animals which had obviously been developed for the purpose. The freight-carrying species was a low, six-legged beast,
very docile and strong but of poor intelligence. The racing animals were of different breed altogether, normal•ly walking on four legs but using only their heavily muscled hind limbs when they really got up speed. They could
cross the entire width of lys in a few hours, and the passenger rode in a pivoted seat strapped on the creature's back. Noth•ing in the world would hav induced alvin to risk such a ride, though it was a very popular sport among the younger men. Their finely bred steeds were the aristocrats of the animal world, and were well aware of it. They had fairly large vocabularies, and alvin often overheard them talking boastfully among themselves about past and future victories. When he tried to be friendly and attempted to join in the con•versation, they pretended that they could not understand him, and if he persisted would go bounding off in outraged dignity. These two varieties of animal sufficed for all ordinary needs, and gave their owners a great deal o pleasure which no mechanical contrivances could have done. But when ex•treme speed was required or vast loads had to be moved, the machines were there, were used without hesitation. Though the animal life of lys presented alvin with a whole world of new interests and surprises, it was the two extremes the human population range that fascinated him most of all. The very young a the very old-both were equally strange to him and equally amazing. Airlee's most senior in•habitant had barely attained his second century, and had only few more years of life before him. When he had reached that age, alvin reminded himself, his body would scarcely have altered, whereas this old man, who had no chain of future existences to look forward to as compensation, ha

almost exhausted his physical powers. His hair was completely white, and his face an unbelievably intricate mass of wrinkles. He seemed to spend most of his time sitting in the sun or walk•ing slowly around the village exchanging soundless greetings with everyone he met. As far as alvin could tell he was com•pletely contented, asking no more of life, and was not dis•tressed by its approaching end. Here was a philosophy so much at variance with that of diaspar as to be completely beyond alvin's comprehension. Why should anyone accept death when it was so unnecessary, when you had the choice of living
a thousand years and then leaping forward through the milenniums to make a n start in a world that you had helped to shape? This was one mystery he was determined to solve as soon as he had the chance of discussing it frankly. was very hard for him to believe that lys had made this choice of its own will, if it knew the alternative that existed. He found part of his answer among the children, those lit•tle creatures who were as strange to him as an of the animals of lys. He spent much of his time among them, watching them their play and eventually being accepted by them as a friend. Sometimes it seemed to him that they were not human at all, their motives, their logic, even their lan•guage were so alien. He would look unbelievingly at the adults and ask himself how it was possible that they could have evolved from these extraordinary creatures who seemed to spend most of their lives in a private world of their own. And yet, even while they baffled him, they aroused withi his heart a feeling he had never known before. When-which was not often, but sometimes happened-they burst into tears of utter frustration or despair,
their tiny disappointments seemed to him more tragic than man's long retreat after the loss of his galactic empire. That was something too huge and remot for comprehension, but the weeping of a child could pierce one to the heart. Alvin had met love in diaspar, but now he was learning something equally precious, and without which love itself could never reach its highest fulfillment but must remain for•ever incomplete. He was learning
tenderness. If alvin was studying lys, lys was also studying him, and was dissatisfied with what it had found. He had been in airlee for three days w seranis suggested that he might like to go further afield and see something more of her country. It was a proposal he accepted at once-on condition that he was not expected to ride one of the village's prize racing beasts. "I ca assure you," said seranis, with a rare flash of humor, "that no one here wo dream of risking one of their pre•cious animals. Since this is an exceptional case, i will arrange transport in which you will feel more at home. Hilvar will act as your guide, but of course you can go wherever you please." alvi wondered if that was strictly true. He imagined that there would be some objection if he tried to return to the little hill from whose summit he had first emerged into lys. How•ever, that did not worry him for the moment sinc he was in no hurry to go back to diaspar, and indeed had given little thou to the problem after his initial meeting with seranis. Life here was still s interesting and so novel that he was still quite content to live in the present. He appreciated seranis's gesture in offering her son as his guide, though doubtless hilvar had been given careful instruc•tions to see that he
did not get into mischief. It had taken alvin some time to get accustomed t hilvar, for a reason which he could not very well explain to him without hurting his feelings. Physical perfection was so universal in diaspar that personal beauty had been completely devalued; men noticed it no more than the air they breathed. This was not the case in lys, and the most flattering adjective that could be applied to hilvar was "homely." by alvin's standards, he was downright ugly, and for a while he had deliberately avoid•ed him. If hilvar was aware of this, he showed no sign of it, and it was not long be his good-natured friendliness had broken through the barrier between them. The time was to come when alvin would be so accustomed to hilvar's broad, twiste smile, his strength, and his gentleness that he could scarcely believe he had ever found him unattractive, and would not have had him changed for any consideration in the world. They left airlee soon after dawn in a small vehicle which hilvar called a ground-car, and which apparently worked on the

same principle as the machine that had brought alvin from diaspar. It floated in the air a few inches above the turf, and although there was no sign of guide rail, hilvar. Told him that the cars could run only on predetermined routes. All the centers of population were linked together in this fashion,
but during his entire stay in lys alvin never saw another ground-car in use. Hilvar had put a great deal of effort into organizing this expedition, and w obviously looking forward to it quite as much as alvin. He had planned the route with his own inter•ests in mind for natural history was his consuming passion and he hoped to find new types of insect life in the relatively uninhabited regions of lys which they would be visiting. He intended to trave as far south as the machine could take them, and the rest of the way they would have to go on foot. Not realizing the full implications of this, alvin made no objections. They had a companion with them on the journey-krif, the most spectacular of hilvar's many pets. When krif was rest•ing, his six gauzy wings lay folded along his body, which glittered through them like a jeweled scepter. If something disturbed him, he would rise into the air with a flick of iridescence and a faint whirring of invisible wings. Though the great
insect would come when called and would-some•times-obey simple orders, it was almost wholly mindless. Yet it had a definite personality of its own, and fo some reason was suspicious of alvin whose sporadic attempts to gain its confidence always ended in failure. To alvin, the journey across lys had a dreamlike unreality. Silent as a ghost, the machine slid across rolling plains and wound its way through forests, never deviating from its in•visible track. It traveled perhaps ten times as fast as a man could comfortably walk: seldo indeed was any inhabitant of lys in a greater hurry than that. They passed through many villages, some larger than air•lee but most of them built along very similar lines. Alvin was interested to notice the subtle but significant differences in clothing and even physical appearance that occurred as they
moved from one community to the next. The civilization of lys was composed o hundreds of distinct cultures, each con•tributing some special talent toward
the whole. The ground•car was well stocked with airlee's most famous product, a small, yellow peach which was gratefully received whenever hilvar gave away some samples. He often stopped to talk to friends and to introduce alvin, wh never ceased to be im•pressed by the simple courtesy with which everyone used vocal speech as soon as thev knew who he was. It must often have been very tedious to them. But as far as he could judge they always resisted the temptation to lapse into telepathy and he never felt excluded from their conversation. They made their longest pause at a tiny village almost hid•den
in a sea of tall golden grass, which soared high above their heads and whic undulated in the gentle wind as if it was endowed with life. As they moved through it, they were continually overtaken by rolling waves as the countless blades bowed in unison above them. At first it was faintly disturb•ing, for alvin had a foolish fancy that the grass was bending down to look at him, after a while he found the continual motion quite restful. Alvin soon discovered why they had made this stop. Among the little crowd that had already gathered before the car came gliding into the village was a shy, dar girl whom hilvar introduced as nyara. They were obviously very pleased to see one another again, and alvin felt envious of their patent hap•piness at this brief reunion. Hilvar was clearly torn between his duties as a guide and his desire to have no other company but nyara, and alvin soon rescued him from quandary by setting off on a tour of exploration by himself. There was not much to see in the little village, but he took his time. When they started their way again, there were many questions he was anxious to ask hilvar. He could not imagine what love must be like in a telepathic society, and after dis•creet interval he broached the subject. Hilvar was willing enough to explain, even though alvin suspected that he had made his friend interrupt a prolonged and tender mental leave•taking. In lys, it seemed, all love began with mental contact, and it might be months or years before a couple actuall met. In this way, hilvar explained, there could be no false impressions, no deceptions on either side. Two people whose minds were open to one another

could hide no secrets if either attempted it, the other partner would know a once that something was being concealed. Only very mature and well-balanced minds could afford such honesty; only love based upon absolute unselfishness could survive it. Alvin could well understand that such a love would be deep and richer than anything his people could know; it could be so perfect, in fact, that he found it hard to believe that it could ever occur at all. Ye hilvar assured him that it did, and became starry-eyed and lost in his own reveries when alvin pressed him to be more explicit. There were some things that could not be com•municated; one either knew them or one did not. Alvin de•cided sadly that he could never attain the kind of mutual un•derstanding which these fortunate people had made tile very basis of their lives. When t ground-car emerged from the savanna, which ended abruptly as though a frontier had been drawn beyond which the grass was not permitted to grow, there was range of low, heavily wooded hills ahead of them. This was an out•post, hilv explained, of the main rampart guarding lys. The real mountains lay beyond,
but to alvin even these small hills were an impressive and awe-inspiring
sight. The car came to a halt in a narrow, sheltered valley which was still flooded by the warmth and light of the descending sun. Hilvar looked at alvi with a kind of wide-eyed candor which, one could have sworn, was totally innocent of any guile. "This is where we start to walk," he said cheerfully, be•ginning to throw equipment out of the vehicle. "We can't ride any farther. alvin looked at the hills surrounding them, then at the com•fortable seat in which he had been riding. "Isn't there a way around?" he asked, not very hopefully. "Of course," replied hilvar. "But we're not going around. We're
going to the top, which is much more interesting. I'll put the car on automatic so that it will be waiting for us) when we get down the other si determined not to give in without a struggle, alvin made one last effort. "I will soon be dark," he protested. "We'll never be able to go all that way before sunset." "exactly," said hilvar, sorting packages and equipment with incredible speed. "We'll spend the night on the summit, and finish the journe in the morning." for once, alvin knew when he was beaten. The gear that the were carrying looked very formidable, but though it was bulky it weighed practically nothing. It was all packed in gravity-polarizing containers that neutralized its weight, leaving only inertia to be contended with. As long as alvin moved in a straight line, he was not conscious that he was carrying a load. Dealing with these containers required a little practice, for if he attempted to make a sudden change of direction his pack seemed to develop a stubborn personality and did its best to keep him on his original course, until he had overcome its momentum. When hilvar had adjusted all the straps and satisfied him•self that everything was in order, they began to walk slowl up the valley. Alvin looked back wistfully as the ground-car retraced its
track and disappeared from sight; he wondered how many hours would elapse before he could again relax in its comfort. Nevertheless, it was very pleasan climbing upward with the mild sun beating on their backs, and seeing ever-new vistas unfold around them. There was a partly obliterated path which
disappeared from time to time but which hilvar seemed able to follow even wh alvin could see no trace of it. He asked hilvar what had made the path. An was told that there were many small animals in these hills-some solitary, and some living in primitive communities whch echoed many of the features of huma civilization. A few had even discovered, or been taught, the use of tools an fire. It never occurred to alvin that such creatures might be other than friendly; both be and hilvar took this for granted, for it had been so many ages since anything on earth had challenged the supremacy of man. They had been climbing for half an hour when alvin first noticed the faint, reverberating murmur in the air around him. He could not detect its source, for it seemed to come from no particular direction. It never ceased, and it grew steadily louder as the landscape widened around them. He would have aske hilvar what it was, but it had become necessary to save his breath for more essential purposes. Alvin was in perfect health; indeed, he had never had an hour's illness in his life. But physical well-being, however im•portant and

necessary it might be, was not sufficient for the task he was facing now. H had the body, but he did not possess the skill. Hilvar's easy strides, the effortless surge of power which took him up every slope, filled alvin with envy -and a determination not to give in while he could still place one foo in front of the other. He knew perfectly well that hilvar was testing him, did not resent the fact. It was a good-natured game, and he entered into th spirit of it even while the fatigue spread slowly through his legs. Hilvar took pity on him when they had completed two-thirds of the ascent and they rested for a while propped up against a westward-facing bank, letting the mellow sunlight drench their bodies. The throbbing thunder was very strong
now, and although alvin questioned him hilvar refused to explain it. It would he said, spoil the surprise if alvin knew, what to expect at the end of th climb. They were now racing against the sun, but fortunately the final ascent was smooth and gentle. The trees that had covered the lower part of the hil had now thinned out, as if they too were tired of the fight against gravity and for the last few hundred yards the ground was carpeted with short, wiry grass on which it was very pleasant to walk. As the summit came in sight, hilvar put forth a sudden burst of energy and went racing up the slope. Alv decided to ignore the challenge; indeed, he had no choice. He was quite content to plod steadi•ly onward, and when he had caught up with hilvar to collapse in contented exhaustion by his side. Not until he had regained his breath was he able to ap•preciate the view spread out beneath him, and to s the origin of the endless thunder which now filled the air. The ground ahead fell away steeply from the crest of the hill•so steeply, indeed, that it soo became an almost vertical cliff. And leaping far out from the face of the cliff was a mighty ribbon of water, which curved out through space to crash into the rocks a thousand feet below. There it was lost in a shimmering mis of spray, while up from the depths rose that ceaseless, drumming thunder that reverberated in hollow echoes from the hills on either side. Most of the waterfall was now in shadow, but the sunlight streaming past the mountain
still illuminated the land beneath, adding the final touch of magic to the scene. For quivering is evanescent beauty above the base of the fall was the last rain•bow left on earth. Hilvar waved his arm in a sweep which embraced the whole horizon. "From here," he said, raising his voice so that it could heard above the thunder of the waterfall, "you can see right across lys." alvin could well believe him. To the north lay mile upon mile of forest, broken here and there by clearings and fields and the wandering threads of a hundred rivers. Hidden some•where in that vast panorama was the village of airlee, but it was hopeless to try to find it. Alvin fancied that he could catch a glimpse of the lake past which the path led to the entrance into l but decided that his eyes had tricked him. Still far•ther north, trees and clearings alike were lost in a mottled carpet of green, rucked here and ther by lines of hills. And beyond that, at the very edge of vision, the mountai that hemmed lys from the desert lay like a bank of distant clouds. East and west the view was little different, but to the south the mountains seemed on a few miles away. Alvin could a see them very clearly, and he realized that they were far higher than the little peak on which he was standing. They we sepa•rated from him by country that was much wilder than the land through which he had just passed. In some indefinable way it seemed deserted and empty, as if man had not lived here for many, many years. Hilvar answered alvin's unspoken question. "Once that part of lys was inhabited," he said. "I don't know why it was abandoned, and perhaps one day we shall move into it again. Only the animals live there now." indeed, there was nowhere any sign human life-none of the clearings or well-disciplined rivers that spoke of
man's presence. Only in one spot was there any indication that he had ever lived here, for many miles away a solitary white ruin jutted above the fores roof like a broken fang. Else•where, the jungle had returned to its own. The sun was sinking below the western walls of lys. For a breathless moment, the
flames; then the land they
the night had come. "We should

have done this before," said hilvar, practical as ever, as he started to unload their equipment. "It'll be pitch dark in five minutes-and cold, too." curious pieces of apparatus began to cover the grass. A slim tripod extended vertical rod carrying a pear-shaped bulge at its upper end. Hilvar raised thi until the pear was just clear of their heads, and gave some mental signal which alvin could not intercept. At once their little encampment was flooded with light, and the darkness retreated. The pear gave not only light but als heat, for alvin could feel a gentle, caressing glow that seemed to sink into his very bones. Carrying the tripod in one hand and his pack in the other, hilvar walked down the slope while alvin hurried behind, do•ing his best to keep in the circle of light. He finally pitched camp in a small depression few hundred yards below the crest of the hill, and started to put the rest his equipment into operation. First came a large hemisphere of some rigid and almost invisible material which englobed them completely and pro•tected them
from the cool breeze which had now begun to blow up the face of the hill. dome appeared to be gen•erated by a small rectangular box which hilvar placed on the ground and then ignored completely, even to the extent of burying it beneath the rest of his paraphernalia. Perhaps this also projected the comfortable, semitransparent couches on which alvin was so glad to relax. It was the first time he had seen furniture materialized in lys, where it seeme to him that the houses were terribly cluttered up with permanent artifacts which would be much better kept safely out of the way in memory banks. The meal which hilvar produced from yet another of his receptacles was also the first purely synthetic one that alvin had eaten since reaching lys. There was a steady blast of air, sucked through some orifice in the dome overhead, as the matter-converter seized its raw material and performed its everyday
miracle. On the whole, alvin was much happier with purely synthetic food. The way in which the other kind was prepared struck him as being appallingly unhygienic, and at least with the matter-converters you knew exactly what you were eating. They settled down for their evening meal as the night deep•ened around them and the stars came out. When they had finished, it was completel dark beyond their circle of light, and at the edge of that circle alvin cou see dim shapes mov•ing as the creatures of the forest crept out of their hiding places. From time to time he caught the glint of reflected light as pale eyes stared back at him, but whatever beasts were watching out there would come no closer, so he could see nothing more of them. It was very peaceful, and alvin felt utterly content. For a while they lay on their couches and talked about the things that they had seen, the mystery that enmeshed them both, and the many ways in which their two cultures differed. Hil•var was fascinated by the miracle of the eternity circuits which had put diaspar beyond the reach of time, and alvin found some of his questions very hard to answer. "What i don't understand," said hilvar, "is how the designers of diaspar made certain that nothing would ever go wrong:, with the memory circuits. You tell me that the information defining the city, and all the people who live in it, is stored as patterns of electric charge inside crystals. Well, crystals will last forever-but what about all the circuits associated with them? Aren't there ever any failures of any kind?" "i asked khedron that same question, and he told me that the memory banks are virtual triplicated. Any one of the, three banks can maintain the city, and if anything goes wrong with one of them, the other two automatically correct it. Only if the same failure occurred simultaneously in two of the banks would a permanent damage be done and the chances of that are infinitesimal." "and how is the relation maintained between the pattern stored in the memory units and the actual structure of the city? Between the plan, as it were, and the thi it describes?" alvin was now completely out of his depth. He knew that the answer involved technologies that relied on the manipula•tion of space
itself-but how one could lock an atom rigidly in the position defined by dat stored elsewhere was some•thing he could not begin to explain. On a sudden inspiration, he pointed to the invisible dome protecting them from the night. "Tell me how this roof above our heads is created by that box you're sittin

on," he answered, "and then i'll explain how the eternity circuits work." hilvar laughed. "I suppose its a fair comparison. You'd have to ask one of field theory experts if you wanted to know that. I certain•ly couldn't tell you." this reply made alvin very thoughtful. So there were still men in lys who understood how their machines worked; that was more than could be said o diaspar. Thus they talked and argued, until presently hilvar said: "i'm tired. What about you-are you going to sleep?" alvin rubbed his still-weary limbs. "I'd like to," he confessed, "but i'm not sure i can. It still seems a str custom to me." "it is a good deal more than a custom," smiled hilvar. "I h been told that it was once a necessity to every human being. We still like sleep at least once a day, even if only for a few hours. During that time body refreshes itself, and the mind as well. Does no one in diaspar ever sleep?" "only on very rare occasions," said alvin. "Jeserac, my tutor, has
done it once or twice, after he had made some exceptional mental effort. A well-designed body should have no need for such rest periods; we did away wi them millions of years ago." even as he spoke these rather boastful words, h actions belied them. He felt a weariness such as he had never before known; seemed to spread from his calves and thighs until it flowed through all his body. There was nothing unpleasant about the sensation-rather the reverse.
Hilvar was watching him with an amused smile, and alvin had enough faculties left to wonder if his companion was exercising any of his mental powers upon him. If so, he did not object in the least. The light flooding down from t metal pear overhead sank to a faint glow, but the warmth it was radiating continued unabated. By the last flicker of light,'alvin's drowsy mind
reg•istered a curious fact which he would have to inquire about in the morning. Hilvar had stripped off his clothes, and for the first time alvin s how much the two branches of the human race had diverged. Some of the chang were merely ones of em•phasis or proportion, but others, such as the external genitals and the presence of teeth, nails, and definite body hair, were more fundamental. What puzzled him most of all, however, was the curious small hollow in the pit of hilvar's stomach. When, some days later, he suddenly remembered the sub•ject, it took a good deal of explaining. By the time that hilvar had made the functions of the navel quite clear, he had uttered many thousands of words and drawn half a dozen diagrams. And both he and alvin h made a great step forward in understanding the basis of each other's
cultures. Twelve The night was at its deepest when alvin woke. Something disturbed him, some whisper of sound that had crept into his mind despite th endless thunder of the falls. He sat up in the darkness, straining his eyes across the hidden land, while with indrawn breath he listened to the drumming roar of the water and the softer, more fugitive sounds of the crea•tures of the night. Nothing was visible. The starlight was too dim to reveal the mile of country that lay hundreds of feet below; only a jagged line of darker ni eclipsing the stars told of the mountains on the southern horizon. In the darkness beside him alvin heard his companion roll over and sit up. "What is it?" came a whispered voice. "I thought i heard a noise." "what sort of noise?" "i don't know: perhaps it was just imagination." there was a silence while two pairs of eyes peered out into the mystery of the night. Then, suddenly, hilvar caught alvin's arm. "Look!" he whispered. Far to the south glowed a solitary point of light, too low in the heavens to be a star. It
a brilliant white, tinged; with violet, and even as they watched it began to climb the spectrum of intensity, until the eye could no longer bear to; look upon it. Then it exploded-and it seemed as if light•ning had struck below th rim of the world. For a brief instant the mountains, and the land they encircled, were etched with fire against the darkness of the night. Ages late came the ghost of a far-off explosion, and in the woods below a sud•den win stirred among the trees. It died away swiftly, and one by one the routed st crept back into the sky. For the second time in his life, alvin knew fear. was not as personal and imminent as it had been in the chamber of the movi ways, when he had made the decision that took him to lys. Perhaps it was a rather than fear; he was look•ing into the face of the unknown, and it was

if he had al•ready sensed that out there beyond the mountains was some•thing he must go to meet. "What was that?" he whispered at length. There was a p so long that he repeated the question. "I am trying to find out," said hilv and was silent again. Alvin guessed what he was doing and did not interrupt his friend's silent quest. Presently hilvar gave a little sigh of disappointment. "Every•one is asleep," he said. "There was no one who could tell me. We must wait until morning, unless i wake one of my friends. And would not like to do that unless it is really important." alvin wondered wha hilvar would consider a matter of real importance. He was just going to suggest, a little sarcasti•cally, that this might well merit interrupting someone's sleep. Before he could make the proposal, hilvar spoke again. "I've just remembered," he said, rather apologetically, "it's a long time since i came here, and i'm not quite certain about my bearings. But that must be shalmirane." "shalmirane! Does it still exist?" "yes; i'd almost forgotten. Seranis once told me that the fortress lies in those mountains. Of course, it's been in ruins for ages, but perhaps someone still lives there." shalmirane! To these children of two races, so widely dif•fering in culture
and history, this was indeed a name of magic. In all the long story of ear there had been no greater epic: than the defense of shalmirane against an invader who had; conquered all the universe. Though the true facts were utter•ly lost in the mists which had gathered so thickly around they dawn ages, the legends had never been forgotten and would last as long as man endured. Presently hilvar's voice came again out of the darkness "the people
of the south could tell us more. I have some friends there; i will call th in the morning." alvin scarcely heard him; he was deep in his own thoughts, trying to remember all that he had ever heard of shalmirane. It was little enough after this immense lapse of time, no one could tell the truth from t legend. All that was certain was that the battle of shalmirane marked the en of man's con•quests and the beginning of his long decline. Among those mountains, thought alvin, might lie the an•swers to all the problems that had tormented him for so many years. "How long," he said to hilvar, "would it t us to reach the fortress?" "i've never been there, but it's much farther tha i intended to go. I doubt if we could do it in a day." "can't we use the ground-car?" "no; the way lies through the mountains and no cars can go there." alvin thought it over. He was tired his feet were sore, and the muscles of his thighs were still aching from the unaccus•tomed effort. It was very tempting to leave it for another time. Yet there might be no other tim Beneath the dim light of the failing stars, not a few of which had died si shalmirane was built, alvin wrestled with his thoughts and presently made his decision. Nothing had changed; the mountains resumed their watch over the sleeping land. But a turning point in history had come and gone, and the hu race was moving toward a strange new future. Alvin and hilvar slept no more that night, but broke camp with the first glow of dawn. The hill was drench with dew, and alvin marveled at the sparkling jewelry which weighed down each blade and leaf. The "swish" of the wet grass fas•cinated him as he plowed through it, and looking back up the hill he could see his path stretching behind him like a dark band across the shining ground. The sun had just lif above the eastern wall of lys when they reached the outskirts of the forest. Here, nature had returned to her own. Even hilvar seemed somewhat lost among the gigantic trees that blocked the sunlight and cast pools of shadow on the jungle floor. Fortunately the river from the fall flowed south in a line too straight to be altogether natural and by keeping to its edge they could avoi the denser under•growth. A good deal of hilvar's time was spent in controllin krif, who disappeared occasionally into the jungle or went skimming wildly across the water. Even alvin, to whom every•thing was still so new, could fe that the forest had a fascina•tion not possessed by the smaller, more cultivated woods of northern lys. Few trees were alike; most of them were in various stages of devolution and some had reverted through the ages almost to their original, natural forms. Many were obviously not of earth at
all-probably not even of the solar system. Watching like sentinels over the

lesser trees were giant sequoias, three or four hundred feet high. Once they had been called the oldest things on earth; they were still a little older than man. The river was widening now; ever and again it opened into small lakes, upon which tiny islands lay at anchor. There were insects here, brilliantly colored creatures swinging to and fro over the surface of the water. Once, despite hilvar's com•mands, krif darted away to join his distant cousins. He dis•appeared instantly in a cloud of glittering wings, and the sound of angry buzzing floated toward them. A moment later the cloud erupted and krif came back across the water, al•most too quickly for the eye to follow. Thereafter he kept very close to hilvar and did not stray again. Toward evening they caught occasional glimpses of the mountains ahead. The
river that had been so faithful a guide was flowing sluggishly now, as if i too were nearing the end of its journey. But it was clear that they could reach the mountains by nightfall; well before sunset the forest had be•come s dark that further progress was impossible. The great trees lay in pools of shadow, and a cold wind was sweeping through the leaves. Alvin and hilvar settled down for the night beside a giant redwood whose topmost branches were still ablaze with sunlight. When at last the hidden sun went down, the light still lingered on the dancing waters. The two explorers-for such they now considered themselves, and such indeed they were -lay in the gathering gloom, watching the river and thinking of all that they had seen. Presently alvin felt once again steal over him that sense of delicious drowsiness he had kno for the first time on the previous night, and he gladly resigned himself to sleep. It might not be needed in the effortless life of diaspar, but he welcomed it here. In the final moment be•fore unconsciousness overcame him, he found himself won•dering who last had come this way, and how long since. The sun was high when they left the forest and stood at last before the mountai walls of lys. Ahead of them the ground rose steeply to the sky in waves of barren rock. Here the river came to an end as spectacular as its beginning, for the ground opened in its path and it sank roaring from sight. Alvin wondered what happened to it, and through what sub•terranean caves it traveled before it emerged again into the light of day. Perhaps the lost oceans of earth still existed, far down in the eternal darkness, and this ancient river still felt the call that drew it to the sea. For a moment hilvar stood loo at the whirlpool and the broken land beyond. Then he pointed to a gap in t hills. "Shalmirane lies in that direction," he said confidently. Alvin did
not ask how he knew; he assumed that hilvar's mind had made brief contact w that of a friend many miles away, and the information he needed had been silently passed to him. It did not take long to reach the gap, and when th had passed through it they found themselves facing a curious plateau with gently sloping sides. Alvin felt no tiredness now, and no fear-only a taut expectancy and a sense of approach•ing adventure. What he would discover, he had no conception. That he would discover something he did not doubt at all. As they approached the summit, the nature of the ground altered abruptly. The lower slopes had consisted of porous, volcanic stone, piled here and there in great mounds of slag. Now the surface turned suddenly to hard, glassy sheets, smooth and treacherous, as if the rock had once rump molten rivers down the mountain. The rim of the plateau was almost at their feet. Hilvar reached it first, and a few seconds later alvin overtook him and stood speechless at hi side. For they stood on the edge, not of the plateau they had expected, but a giant bowl half a mile deep and three miles in diameter. Ahead of them t ground plunged steeply downward, slowly leveling out at the bottom of the valley and rising again, more and more steeply, to the opposite rim. The lowest part of the bowl was occupied by a circular lake, the surface of whi trembled continually, as if agitated by incessant waves. Although it lay in
the full glare of the sun, the whole of that great depression was ebon blac What material formed the crater, alvin and hilvar could not even guess, but was black as the rock of a world that had never known a sun. Nor was that for lying beneath their feet and ringing the entire crater was a seamless ba of metal, some hundred feet wide, tarnished by immeasurable age but still

showing no slightest sign of corrosion. As their eyes grew accustomed to the unearthly scene, alvin and hilvar realized that the blackness of the bowl was not as absolute as they had thought. Here and there, so fugi•tive that they could only see them indirectly, tiny explosions of light were flickering in
the ebon walls. They came at ran•dom, vanishing as soon as they were born, like the reflections of stars on a broken sea. "It's wonderful!" gasped alvin "But what is it?" "it looks like a reflector of some kind." "but it's so black!" "only to our eyes, remember. We do not know what radia•tions they used." but surely there must be more than thisl where is the fortress?" hilv pointed to the lake."look carefully," he said. Alvin stared through the quivering roof of the lake, try•ing to plumb the secrets it concealed within its depths. At first he could see nothing; then, in the shallows near its edge, he made out a faint reticulation of light and shade. He was able to trace the pattern out toward the center of the lake until the deepening wate hid all further details. The dark lake had engulfed the fortress. Down there lay the ruins of once mighty buildings, overthrown by time. Yet not all of them had been submerged, for on the far side of the crater alvin now notice piles of jumbled stones, and great blocks that must once have formed part of massive walls. The waters lapped around them, but had not yet risen far enou to complete their victory. "We'll go around the lake," said hilvar, speaking softly as if the majestic desolation had struck awe into his soul. "Perhaps may find something in those ruins over there." for the first few hundred yar the crater walls were so steep and smooth that it was difficult to stand upright, but after a while they reached the gentler slopes and could walk without difficulty. Near the border of the lake the smooth ebony of the surface was concealed by a thin layer of soil, which the winds of lys must have brought here through the ages. A quarter of a mile away, titanic blocks of stone were piled one upon the other, like the discarded toys of an infan giant. Here, a section of a massive wall was still recognizable; there, two careen obelisks marked what had once been a mighty entrance. Everywhere grew mosses and creeping plants, and tiny stunted trees. Even the wind was hushed. So alvin and hilvar came to the ruins of shalmirane. Against those walls, an against the energies they had housed, forces that could shatter a world to dust had fumed and thundered and been utterly defeated. Once these peaceful skies had blazed with fires torn from the hearts of suns, and the mountains lys must have quailed like living things beneath the fury of their masters. one had ever captured shalmirane. But now the for•tress, the impregnable fortress, had fallen at last-captured and destroyed by the patient tendrils of the ivy, the genera•tions of blindly burrowing worms, and the slowly rising waters of the lake. Overawed by its majesty, alvin and hilvar walked in si•lence toward the colossal wreck. They passed into the shadow of a broken wall, and entered a canyon where the mountains of stone had split asunder. Before them lay the lake, and pres•ently they stood with the dark water lapping at their feet. Tiny waves, no more than a few inches high, broke endlessly upon the narrow shore. Hilvar was the first to speak, and his voic held a hint of uncertainty which made alvin glance at him in sudden sur•pris "There's something here i don't understand," he said slow•ly. "There's no
wind, so what causes these ripples? The watershould be perfectly still."
before alvin could think of any reply, hilvar dropped tothe ground, turned hi head on one side and immersed his right ear in the water. Alvin wondered wh he hoped to dis•cover in such a ludicrous position; then he realized that he was listening. With some repugnance-for the rayless waters looked singularly uninviting-he followed hilvar's example. The first shock of coldness lasted
only for a second; when it passsed he could hear, faint but distinct, a steady, rhythmic throbbing. It was as if he could hear, from far down in th depths of the lake, the beating of a giant heart. They shook the water from their hair and stared at each other with silent surmise. Neither liked to sa what he thought that the lake was alive. "It would be best," said hilvar presently, "if we searched among these ruins and kept away from the lake." " you think there's something down there?" asked alvin, pointing to the

enigmatic ripples that were still breaking against his feet. "Could it be dangerous?" "nothing that possesses a mind is dangerous," hilvar re•plied. (Is that true? Thought alvin. What of the invaders?) "i can detect no thoughts o any kind here, but i do not be•lieve we are alone. It is very strange." th walked slowly back toward the ruins of the fortress, each carrying in his mi the sound of that steady, muffled pulsing. It seemed to alvin that mystery w piling upon mys•tery, and that for all his efforts he was getting further an further from any understanding of the truths he sought. It did not seem that the ruins could teach them anything, but they searched carefully among the piles of rubble and the great mounds of stone. Here perhaps, lay the graves buried machines-the machines that had done their work se long ago. They would be useless now, thought alvin, if the invaders returned. Why had they never come back? But that. Was yet another mystery: he had enough enigmas to deal with -there was no need to seek for any more. A few yards from the lake t found a small clearing among the rubble. It had been covered with weeds, but they were now blackened and charred by tremendous heat, so that they crumbled to ashes as alvin and hilvar approached, smearing their legs with streaks of charcoal. At the center of the clearing stood a metal tripod, firmly anchored to the ground, and supporting a circular ring which was tilted on its axis that it pointed to a spot halfway up the sky. At first sight it seemed tha the ring enclosed nothing; then, as alvin looked more carefully, he saw that it was filled with a faint haze that tormented the eye by lurking at the e of the visible spectrum. It was the glow of power, and from this mechanism did not doubt, had come the explosion of light that had lured them to shalmirane. They did not venture any closer, but stood looking at the machine from a safe distance. They were on the right track, thought alvin; now it o remained to discover who, or what, had set this apparatus here, and what the purpose might be. That tilted ring-it was clearly aimed out into space. Had the flash they had observed been some kind of signal? That was a thought wh had breath-taking implications. "Alvin," said hilvar suddenly, his voice quiet but urgent, "we have visitors." alvin spun on his heels and found himself staring at a triangle of lidless eyes. That, at least, was his first impression; then behind the staring eyes he saw the outlines of a small but complex machine. It was hanging in the air a few feet above the ground, and was like no robot he had ever before seen. Once the initial surprise had wo off, he felt himself the complete master of the situation. All his life he given orders to machines, and the fact that this one was unfamiliar was of importance. For that matter, he had never seen more than a few per cent of robqts that provided hip daily needs in diaspar. "Can you speak?" he asked. There was silence. "Is anyone controlling you?" still silence. "Go away. Come here. Rise. Fall." none of the conventional control thoughts produced any effect. The machine remained contemptuously inactive. That suggested two possibilities. It was either too unintelligent to understand lion or it was very intelligent indeed, with its own powers of choice and volition. In that case, he must treat it as an equal. Even then he might underestimate it, bu it would bear him no resentment, for conceit was not a vice from which robo often suffered. Hilvar could not help laughing at alvin's obvious
discom•fiture. He was just about to suggest that he should take over the tas of communicating, when the words died on his lips the stillness of shalmirane was shattered by an ominous and utterly unmistakable sound-the gurgling splash of a very large body emerging from water. It was the second time since he left diaspar that alvin wished he were at home. Then he remembered that this was not the spirit in which to meet adventure, and he began toe walk slowly but deliberately toward the lake. The creature now emerging from the dark
water seemed a monstrous parody, in living matter, of the robot that was sti subjecting them to its silent scrutiny. That same equilateral arrangement of eyes could be no coincidence; even the pat•tern of tentacles and little
jointed limbs had been roughly re•produced. Beyond that, however, the
resemblance ceased. The robot did not possess-it oviously did not require• the fringe of delicate, feathery palps which beat the water with a steady rhythm,

the stubby multiple legs on which the beast was humping itself ashore, or th ventilating inlets, if that was what they were, which now wheezed fitfully in the thin air. Most of the creature's body remained in the water; only the first ten feet reared itself into what was clearly an alien ele•ment. The entire beast was about fifty feet long, and even anyone with no knowledge of biology would have realized that there was something altogether wrong about
it. It had as extraordinary air of improvisation and careless design, as if its components had been manufactured without much fore•thought and thrown roughly together when the need arose. Despite its size and their initial doubts, neither alvin nor hilvar felt the slightest nervousness once they had
had a clear look at the dweller in the lake. There was an engaging clumsi•n about the creature which made it quite impossible to re•gard it as a serious menace, even if there was any reason to suppose it might be dangerous. The human race had long ago overcome its childhood terror of the merely alien in appear•ance. That was a fear which could no longer survive after the first contact with friendly extraterrestrial races. "Let me deal with this," said hilvar quietly. "I'm used to handling animals." "but this isn't an animal," whispered alvin in return. "I'm sure it's intelligent, and owns that robot." "the robot may own it. In any case, its mentality must be very strange. I still detect no sign of thought. Hello •what's happening?" the monster had no moved from its half-raised position at the water's edge, which it seemed to maintaining with considerable effort. But a semitransparent membrane had
be•gun to form at the center of the triangle of eyes-a membrane that pulsed and quivered and presently started to emit audible sounds. They were
low-pitched, resonant boomings which created no intelligible words, though it
was obvious that the creature was trying to speak to them. It was painful t watch this desperate attempt at communi•cation. For several minutes the
creature struggled in vain; then, quite suddenly, it seemed to realize that i had made a mistake. The throbbing membrane contracted in size, and the sounds it emitted rose several octaves in frequency until they entered the spectrum
of normal speech. Recognizable words began to form though they were still interspersed with gibberish. It was as if the creature was remembering a vocab•ulary it had known long ago but had had no occasion to use for many years. Hilvar tried to give what assistance be could. "We can understand you now," he said speaking slowly and distinctly. "Can we help you? We saw the light you made. It brought us here from lys." at the word "lys" the creatur seemed to droop as if it had suffered some bitter disappointment. "Lys," it repeated; it could not manage the "s" very well, so that the word sounded l "lyd." "always from lys- no one else ever comes. We call the great ones, bu they do not hear." "who are the great ones?" asked alvin, leaning forward eagerly. The delicate, ever-moving palps waved briefly to•ward the sky. "The great ones," it said. "From the planets of eternal day. They will come. The master promised us." this did not seem to make matters any clearer. Before alvin could continue his cross-examination, hilvar intervened again. His questioning was so patient, so sympathetic, and yet so penetrating that alvin knew better than to interrupt, despite his eagerness. He did not like to adm that hilvar was his superior in intelligence, but there was no doubt that hi flair for handling animals extended even to this fantastic being. What was more, it seemed to respond to him. Its speech be•came more distinct as the conversation proceeded, and where at first it had been brusque to the point rudeness, it present•ly elaborated its answers and volunteered information on
its own alvin lost all consciousness of the passage of time as hil•var piece together the incredible story. They could not dis•cover the whole truth; there was endless room for conjecture and debate. As the creature answered hilvar's questions ever more and more willingly, its appearance began to change. It slumped back into the lake, and the stubby legs that had been supporting it seemed to dissolve into the rest of its body. Pres•ently a still more extraordinary change occurred; the three huge eyes slowly closed, shrank to pinpoints, and vanished completely. It was as if the creature had seen all that it wished to for the moment, and therefore had no further use for eyes

Other and more subtle alterations were continually taking place, and
eventually almost all that remained above the sur•face of the water was the vibrating diaphragm through which the creature spoke. Doubtless this too would be dissolved back into the original amorphous mass of protoplasm when it was no longer required. Alvin found it hard to believe that intelligence could reside in so unstable a form-and his biggest surprise was yet to come. Thoug it seemed obvious that the creature was not of terrestrial origin, it was so time before even hilvar, despite his greater knowledge of biology, realized
the type of organism they were dealing with. It was not a single entity; in all their conversations with it, it always referred to itself as "we." in fact, it was nothing less than a colony of inde•pendent creatures, organized and controlled by unknown forces. Animals of a remotely similar type the medusae, for ex•ample-had once flourished in the ancient oceans of earth. Some of them had been of great size, trailing their translucent bodies and forests of stinging tentacles over fifty or a hundred feet of water. But none of th had attained even the faintest flicker of intelligence, beyond the power to re•act to simple stimuli. There was certainly intelligence here, though it was a fail•ing, degenerating intelligence. Never was alvin to forget this
unearthly meeting, as hilvar slowly pieced together the story of the master, while the protean polyp groped for unfamiliar words, the dark lake lapped at the ruins of shalmirane, and the trioptic robot watched them with unwavering eyes. Thirteen The master had come to earth amid the chaos of the transi centuries, when the galactic empire was crumb•ling but the lines of communication among the stars had not yet completely broken. He had been of human origin, though his home was a planet circling one of the seven suns. While still a young man, he had been forced to leave his native world, and memory had haunted him all his life. His ex•pulsion he blamed on vindictive enemies, but the fact was that he suffered from an incurable malady which, i seemed, at•tacked only homo sapiens among all the intelligent races of the universe. That disease was religious mania. Throughout the earlier part of its history, the human race had brought forth an endless succession of prophets, seers, messiahs, and evangelists who convinced themselves and their followers that to them alone were the secrets of the universe revealed. Some of them succeeded in establishing religions that survived for many generations and influenced billions of men; others were forgotten even before their deaths.
The rise of science, which with montonous regularity re•futed the cosmologies
of the prophets and produced miracles which they could never match, eventually destroyed all these faiths. It did not destroy the awe, nor the reverence an hu•mility, which all intelligent beings felt as they contemplated the
stupendous universe in which they found themselves. What it did weaken and finally obliterate, were the countless religions, each of which claimed with unbelievable arrogance, that it was the sole repository of the truth and that its millions of rivals and predecessors were all mistaken. Yet, though they never possessed any real power once humanity had reached a very elementary level of civilization, all down the ages isolated cults had continued to ap•pear, and however fantastic their creeds they had always managed to attract some disciples. They thrived with party p cular strength during periods of confusion and disorder, and 1 it was not surprising that the transition centuries had seen a great outburst of irrationality. When reality was depressing, men tried to console themselves with myths. The master, even if h was expelled from his own world, did not leave it unprovided. The seven suns had been the center of galactic power and science, and he must have pos•sess influential friends. He had made his hegira in a small but speedy ship, reputed to be one of the fastest ever built. With him into exile he had ta another of the ultimate products of galactic science-the robot that was
looking at alvin and hilvar even now. No one had ever known the full talent and functions of this machine. To some extent, indeed, it had become the master's alter ego; without it, the religion of the great ones would probably have collapsed after the master's death. To•gether they had roved among the star clouds on a zigzag trail which led at last, certainly not by accident,

back to the world from which the master's ancestors had sprung. Entire libraries had been written about that saga, each work therein inspiring a hos of commentaries until, by a kind of chain reaction, the original volumes were lost beneath moun•tains of exegesis and annotation. The master had stopped at many worlds, and made disciples among many races. His per•sonality must have been an immensely powerful one for it to have inspired humans and nonhumans alike, and there was no doubt that a religion of such wide appeal must have con•tained much that was fine and noble. Probably the master was the most successful-as he was also the last-of all man•kind's messiahs. None of his predecessors could have won so many converts or had their teachings carried across such gulfs of time and space. What those teachings were neither alvin nor hilvar could ever discover with any accuracy. The great polyp did its des•perate best to convey them, but many of the words it used were meaningle and it had a habit of repeating sentences or whole speeches with a kind of swift mechanical delivery that made them very hard to follow. After a while hilvar did his best to steer the conversation away from these meaningless morasses of theology in order to concentrate on ascertainable facts. The
master and a band of his most faithful followers had arrived on earth in th days before the cities had passed away, and while the port of diaspar was still open to the stars. They must have come in ships of many kinds; the polyps, for example, in one filled with the waters of the sea which was the natural home. Whether the movement was well re•ceived on earth was not
certain; but at least it met no violent opposition, and after further wanderings it set up its final re•treat among the forests and mountains of lys. At the close of his long life, the master's thoughts had turned once m toward the home from which he had been exiled, and he had asked his friends carry him out into the open so that he could watch the stars. He had waite his strength waning, until the culmination of the seven suns, and toward the end he babbled many things which were to inspire yet more libraries of interpretation in future ages. Again and again he spoke of the "great ones" who had now left this universe of space and matter but who would surely one day return, and he charged his followers to remain to greet them when they came. Those were his last rational words. He was never again conscious of hi surroundings, but just before the end he uttered one phrase that had come do the ages to haunt the minds of all who heard it: "it is lovely to watch t colored shadows on the planets of eternal light." then he died. At the master's death, many of his followers broke away, but others remained faithful to his teachings, which they slowly elaborated through the ages. At first the believed that the great ones, whoever they were, would soon return, but that hope faded with the passing centuries. The story here grew very confused, and it seemed that truth and legend were inextricably intertwined. Alvin had only
a vague picture of generations of fanatics, waiting for some great event whic they did not understand to take place at some unknown future date. The great ones never returned. Slowly the power of the movement failed as death and disillusion robbed it of its dis•ciples. The short-lived human followers were the first to go, and there was something supremely ironic in the fact that very last adherent of a human prophet was a creature ut•terly unlike man. Th great polyp had become the master's last disciple for a very simple reason. was immortal. The billions of indi•vidual cells from which its body was built would die, but before that happened they would have reproduced themselves. At long intervals the monster would disintegrate into its myr•iad separate cells which would go their own way and multi•ply by fission if their environment w suitable. During this phase the polyp did not exist as a self-conscious intelligent entity-here alvin was irresistibly reminded of the manner in which the inhabitants of diaspar spent their quiescent mil•lenniums in the city's memory banks. In due time some mysterious biological force brought the
scattered components together again, and the polyp began a new cycle of existence. It returned to awareness and recol•lected its earlier lives, though often imperfectly since accident sometimes damaged the cells that carried the delicate patterns of memory. Perhaps no other form of life could have kept

faith so long to a creed otherwise forgotten for a billion years. In a sense,the great polyp was a helpless victim of its biological nature. Because of its immortality, it could not change, but was forced to repeat eternally the same invariant pattern. The religion of the great ones, in its later stages, had be•come identified with a veneration of the seven suns. When the great ones stubbornly refused to appear, attempts were made to signal their distant home. Long ago the signaling had become no more than a meaningless ritual, now maintained by an animal that had forgotten how to learn and a robot that had never known how to forget. As the immeasurably ancient voice died away into the still air, alvin found himself overwhelmed by a surge of pity. The misplaced devotion, the loyalty that had held to its futile cou while suns and planets passed away-he could never have believed such a tale had he not seen the evidence before his eyes. More than ever before the ext of his ignorance saddened him. A tiny fragment of the past had been illumi•nated for a little while, but now the darkness had closed over it again. The history of the universe must be a mass of such dis•connected threads, and no one could say which were im•portant and which were trivial. This fantastic tale of the master and the great ones seemed like another of the count•less legends that had somehow survived from the civilizations of the dawn. Yet the very existence of the huge polyp, and of the silently watching robot, made it impossible for alvin to dismiss the whole story as a fable built of self-delusion up•on a foundation of madness. What was the
relationship, he wondered, between these two entities, which though so different in every possible way had maintained their extraordinary partnership over such aeons of time? He was somehow certain that the robot was much the more important of the two. It had been the confi•dant of the master and mus still know all his secrets. Alvin looked at the enigmatic machine that still regarded him so steadily. Why would it not speak? What thoughts were passing through its complicated and perhaps alien mind? Yet, surely, if it had been designed to serve the master, its mind would not be altogether alien, and it should respond to hu•man orders. As he thought of all the secrets which that stubbornly mute machine must possess, alvin felt a curiosity so great that it verged upon greed. It seemed unfair that such knowledge should be wasted and hidden from the world; here must lie wonders beyond even the ken of the central computer in diaspar. "Why won't your robot speak to us?" he asked th polyp, when hilvar had momentarily run out of questions. The answer was one had half expected. "It was against the master's wishes for it to speak with any voice but his, and his voice is silent now." "but it will obey you?" " the master placed it in our charge. We can see through its eyes, wherever i goes. It watches over the machines that preserve this lake and keep its wate pure. Yet it would be truer to call it our partner than our servant." alvin thought this over. An idea, still vague and half•formed, was beginning to tak shape in his mind. Perhaps it was inspired by pure lust for knowledge and power; when he looked back on this moment he could never be certain just wh his motives were. They might be largely selfish, but they also contained some element of compassion. If he could do so, he would like to break this futil sequence and release these creatures from their fantastic fate. He was not
sure what could be done about the polyp, but it might be possible to cure robot of its insanity and at the same time to release its priceless, pent-up memories. "Are you certain," he said slowly, talking to the polyp but aiming his words at the robot, "that you are really carrying out the master's wishe by remaining here? He desired the world to know of his teaching, but they h been lost while you hide here in shalmirane. It was only by chance that we discovered you, and there may be many others who would like to hear the doctrine of the great ones." hilvar glanced at him sharply, obviously
uncertain of his intentions. The polyp seemed agitated, and the steady beating of its respiratory equipment faltered for a few seconds. Then it replied, in voice not altogether under control: "we have discussed this problem for many years. But we cannot leave shalmirane, so the world must come to us, no mat how long it takes." "i have a better idea," said alvin eagerly. "It is true

that you may have to stay here in the lake, but there is no reason why yo companion should not come with us. He can return whenever he wishes or whenever you need him. Many things have changed since the master died-things which you should know about, but which you can never understand if you stay here." the robot never moved, but in its agony of indecision the polyp sank completely below the surface of the lake and re•mained there for several minutes. Perhaps it was having a soundless argument with its colleague;
several times it began to re-emerge; thought better of it, and sank into the water again. Hilvar took this opportunity to exchange a few words with alvin. "I'd like to know what you are trying to do," he said softly, his voice
half-bantering and half-serious. "Or don't you know yourself?" "surely,"
replied alvin, "you feel sorry for these poor creatures? Don't you think it would be a kindness to rescue them?" "i do, but i've learned enough about y to be fairly certain that altruism isn't one of your dominant emotions. You must have some other motive." alvin smiled ruefully. Even if hilvar did not read his mind-and he had no reason to suppose that he did-he could undoubted read his character "your people have remarkable mental powers," he re•plied, trying to divert the conversation from dangerous ground. "I think they might
be able to do something for the robot, if not this animal." he spoke very softly, lest he be overheard. The precaution might have been a useless one, but if the robot did intercept his remarks it gave no sign of it. Fortunate before hilvar could press the inquiry any further, the polyp emerged once mor from the lake. In the last few minutes it had become a good deal smaller a its movements were more disorganized. Even as alvin watched, a segment of its complex, translucent body broke away from the main bulk and then disintegrated into multitudes of smaller sections, which swiftly dispersed. The creature was beginning to break up before their eyes. Its voice, when it spoke again, was very erratic and hard to understand. "Next cycle starting," it jerked out in kind of fluctuat•ing whisper. "Did not expect it so soon-only few minutes
left-stimulation too great--cannot hold together much longer." alvin and hilvar stared at the creature in horrified fas•cination. Even though the process they were watching was a natural one, it was not pleasant to watch
intelligent creature apparently in its death throes. They also felt an obscure sense of guilt; it was irrational to have the feeling, since it was of no great importance when the polyp began another cycle, but they realized that
the unusual effort and excitement caused by their presence was responsible for this premature metamorphosis. Alvin realized that he would have to act quickly or his opportunity would be gone perhaps only for a few years, perhaps for centuries. "What have you decided?" he said eagerly. "Is the robot coming wit us?" there was an agonizing pause while the polyp tried to force its dissolving body to obey its will. The speech di•aphragm fluttered, but no audible sound came from it. Then, as if in a despairing gesture of farewell, it waved its delicate palps feebly and let them fall back into the water, where they promptly broke adrift and went floating out into the lake. In a matter of minutes, the transformation was over. Nothing of the creature larger than an inch across remained. The water was full of tiny, greenish specks, which seemed to have a life and mobility of their own and which rapidly disappeared into the vastness of the lake. The ripples on the surface had no altogether died away, and alvin knew that the steady pulse beat that had sounded in the depths would now be stilled. The lake was dead again -or so seemed. But that was an illusion; one day the un•known forces that had never failed to do their duty in the past would exert themselves again, and the polyp would be reborn. It was a strange and wonderful phenomenon, yet was it so much stranger than the organization of the human body, itself a vast colo of separate, living cells? Alvin wasted little effort on such speculations. He was oppressed by his sense of failure, even though he had never clearly conceived the goal he was aiming for a dazzling opportunity had been missed and might never again return. He stared sadly out across the lake, and it w some time before his mind registered the message which hilvar was speaking quietly in his ear. "Alvin," his friend said softly, "i think you have won

your point." he spun swiftly on his heels. The robot, which until now had b floating aloofly in the distance, never approaching within twenty feet of
them, had moved up in silence and was now poised a yard above his head. It unmoving eyes, with their wide angles of vision, gave no indication of its direction of interest. Probably it saw the entire hemisphere in front of it with equal clarity, but alvin had little doubt that its attention was now focused upon him. It was waiting for his next move. To some extent, at leas it was now under his control. It might follow him to lys, per•haps even to diaspar-unless it changed its mind. Until then, he was its probationary
master. Fourteen The journey back to airlee lasted almost three days•partly because alvin, for his own reasons, was in no hurry to return. The physical exploration of lys had now taken second place to a more important and exciti project; he was slowly making contact with the strange, obsessed intel•ligence which had now become his companion. He suspected that the robot was trying t use him for its own purposes, which would be no more than poetic jus•tice.
What its motives were he could never be quite certain, since it still stubbornly refused to speak to him. For some reason of his own-perhaps fear that it might reveal too many of his secrets-the master must have placed ver ef•ficient blocks upon its speech circuits, and alvin's attempts to clear them were completely unsuccessful. -Even indirect questioning of the "if you say nothing i shall assume you mean `yes " type failed; the robot was much too intelligent to be taken in by such simple tricks. In other respects, however, it was more cooperative. It would obey any orders that did not require it t speak or reveal information. After a while alvin found that he could control it, as he could direct the robots in diaspar, by thought alone. This was a great step forward, and a little later the creature-it was hard to think of as a mere machine-re•laxed its guard still further and allowed him to see through its eyes. It did not object, it seemed, to such passive forms of communication, but it blocked all attempts at closer in•timacy. Hilvar's existence it ignored completely; it would obey none of his commands, and its mind was closed to all his probing. At first this was something of a disappointment to alvin, who had hoped that hilvar's greater mental powers
would enable him to force open this treasure chest of hidden mem•ories. It w not until later that he realized the advantage of possessing a servant who would obey no one else in all the world. The member of the expedition who strongly objected to the robot was krif. Perhaps he imagined that he now had rival, or perhaps he disapproved, on general principles, of anything that flew without wings. When no one was looking, he had made several direct assaults the robot, which had infuriated him still further by taking not the slightest notice of his attacks. Eventually hilvar had been able to calm him down, and on the homeward journey in the ground-car he seemed to have resigned himself to the situation. Robot and insect escorted the vehicle as it glided silently through forest and field-each keeping to the side of its respective master an pretending that its rival was not there. Seranis was already waiting for them as the car floated into airlee. It was impossible, alvin thought, to surprise these people. Their interlinked minds kept them in touch with everything that was happening in their land. He wondered how they had reacted to his adventures in shalmirane, which presumably everyone in lys now knew about. Seranis seemed to be worried and more uncertain than he had ever seen her before, and alvin remembered the choice that now lay before him. In the excitement of the last few days he had almost forgotten it; he did not like spend energy worrying about problems that still lay in the future. But the future was now upon him; he must decide in which of these two worlds he wi to live. The voice of seranis was troubled when she began to speak, and alv had the sudden impression that something had gone awry with the plans that l had been making for him. What had been happening during his absence? Had emis•saries gone into diaspar to tamper with khedron's mind-and had they
failed in their duty? "Alvin," began seranis, there are many things i did no tell you before, but which you must now learn if you are to understand our actions." "you know one of the reasons for the isolation of our two races.

fear of the invaders, that dark shadow in the depths of every human mind, turned your people against the world and made them lose themselves in their own dreams. Here in lys that fear has never been so great, though we bore burden of the final attack. We had a better reason for our actions, and wha we did, we did with open eyes. "Long ago, alvin, men sought immortality and last achieved it. They forgot that a world which had banished death must als banish life. The power to extend his life indefinitely might bring contentment to the individual, but brought stag•nation to the race. Ages ago we sacrifice our immortality, but diaspar still follows the false dream. That is why our ways parted-and why they must never meet again." although the words had been more than half expected, the blow seemed none the less for its anticipation. Yet alvin refused to admit the failure of all his plans-half-formed though
they were and only part of his brain was listening to seranis now. He understood and noted all her words, but the conscious portion of his mind wa retracing the road to diaspar, trying to imagine every obstacle that could be placed in his way. Seranis was clearly unhappy. Her voice was almost plead•in as it spoke, and alvin knew that she was talking not only to him but to h son. She must be aware of the under•standing and affection that had grown up between them dur•ing the days they had spent together. Hilvar was watching hi mother intently as she spoke, and it seemed to alvin that his gaze held not merely concern but also more than a trace of censure. "We do not wish to m you do anything against your will, but you must surely realize what it would mean if our people met again. Between our culture and yours is a gulf as g as any that ever separated earth from its ancient colonies. Think of this on fact, alvin. You and hilvar are now of nearly the same age but both he and will have been dead for centuries while you are still a youth. And this is only your first in an infinite series of lives." the room was very quiet, s quiet that alvin could hear the strange, plaintive cries of unknown beasts in the fields beyond the village. Presently, he said, almost in a whisper: "what do you want me to do?" "we hoped that we could give you the choice of sta here or returning to diaspar, but now that is impossible. Too much has happened for us to leave the decision in your: hands. Even in the short tim you have been here, your in•fluence has been highly disturbing. No, i am not reproving you; i am sure you intended no harm. But it would have been best leave the creatures you met in shalmirane to their own destiny. "And as for diaspar-" seranis gave a gesture of annoy•ance. "Too many people know where
you have gone; we did not act in time. What is most serious, the man who helped you discover lys has vanished; neither your council nor our agents can discover him, so he remains a potential danger to our security. Perhaps you are surprised that i am telling you all this, but it is quite safe for me do so. I am afraid we have only one choice before us; we must send. You b to diaspar with a false set of memories. Those memories have been constructed with great care, and when you return home you will know nothing of us. You will: believe that you have had rather dull and dangerous ad•ventures in
gloomy underground caverns, where the roofs continually collapsed behind you and you kept alive only through eating unappetizing weeds and drinking from oc•casional springs. For the rest of your life you will believe this to be truth, and everyone in diaspar will accept your story. There will be no mystery, then, to lure any future explorers; they will think they know all there is to be known about lys." Seranis paused and looked at alvin with anxious eyes. "We are very sorry that this is necessary and ask your for•giveness while you still remember us. You may not accept our verdict, but we know many facts that are hidden from you. At least you will have no regrets, for you will believe that you have discovered all that there is to found." alvin wondered if that was true. He was not sure that he would ever settle down to the routine of life in diaspar, even when he had convinced himself that nothing worth•while existed beyond its walls. What was more, he had no intention of putting the matter to the test. "When do you wish me t undergo this-treatment?" alvin asked. "Immediately. We are ready now. Open
your mind to me, as you did before, and you will know nothing until you fi

yourself back in diaspar." alvin was silent for a while. Then he said quietl "i would like to say good-by to hilvar." seranis nodded. "I understand. I wi leave you here for a while and return when you are ready." she walked over the stairs that led down to the interior of the house, and left them alone the roof. It was some time before alvin spoke to his friend; he felt a gre sadness, yet also an unbroken determination not to permit the wreck of all h hopes. He looked once more down upon the village where he had found a measu of happiness and which he might never see again if those who were ranged behind seranis had their way. The ground-car was still stand•ing beneath one
of the wide-branching trees, with the patient robot hanging in the air above it. A few children had gathered around to examine this strange newcomer, but none of the adults seemed in the least interested. "Hilvar," said alvin abruptly, "i'm very sorry about this:" "so am i," hilvar answered, his voice unstable with emo•tion. "I had hoped that you could have remained here." "do you think that what seranis wants to do is right?" "do not blame my mother. She is only doing as she is asked," replied hilvar. Though he had not answe his question, alvin had not the heart to ask it again. It was unfair to pu such a strain on his friend's loyalty. "Then tell me this," asked alvin, "ho could your peo•ple stop me if i tried to leave with my memories untouched?" "it would be easy. If you tried to escape, we would take control of your m and force you to come back." alvin had expected as much and was not discouraged. He wished that he could confide in hilvar, who was obviously
upset by their impending separation, but he dared not risk the failure of hi plans. Very carefully, checking every de•tail, he traced out the only road
that could lead him back to iaspar on the terms he wished. There was one r which he had to face, and against which he could do nothing to protect himself. If seranis broke her promise and dipped into his mind, all his careful prepara•tions might be in vain. He held out his hand to hilvar, who grasped it firmly but seemed unable to speak. "Let's go downstairs to meet seranis," said alvin. "I'd like to see some of the people in the village before i go." hilvar followed him silently into the peaceful coolness of the house and then out through the hallway and onto the ring of colored glass t surrounded the building. Seranis was waiting for them there, looking calm and resolute. She knew that alvin was trying to hide something from her, and thought again of the precautions she had taken. As a man may flex his muscl before some great effort, she ran through the compulsion patterns she might have to use. "Are you ready, alvin?" she asked. "Quite ready," replied alvin, and there was a tone in his voice that made her look at him sharply. "Then will be best if you make your mind a blank, as you did before. You will f and know nothing after that, until you find yourself back in diaspar." alvin turned to hilvar and said m a quick whisper that seranis could not hear: "good-by, hilvar, don't worry• i'll be back." then he faced seranis again. "I don't resent what you are trying to do," he said. "No doubt you believe it for the best, but i think you are wrong. Diaspar and lys should not remain apart forever; one day they may need each other desperately. So i am going home with all that i have learned-and 1 do not think that you can stop me. waited no longer, and it was just as well. Seranis never moved, but instantl he felt his body slipping from his con•trol. The power that had brushed asid his own will was even greater than he had expected, and he realized that ma hidden minds must be aiding seranis. Helplessly he began to walk back into t house, and for an awful moment he thought his plan had failed. Then there c a flash of steel and crystal, and metal arms closed swiftly around him. His body fought against them, as he had known that it must do, but the struggle were use•less. The ground fell away beneath him and he caught a glimpse of hilvar, frozen by surprise, with a foolish smile upon his face. The robot wa carrying him a dozen feet above the ground, much faster than a man could ru It took seranis only a moment to understand his ruse, and his struggles died away as she relaxed her control. But she was not defeated yet, and presently

was pleading with the robot, begging it to set him down. The real alvin waited, breathlessly, re•sisting only a little against forces he knew he could not hope to fight. He had gambled; there was no way of telling be•forehand his uncertain ally would obey orders as complex as those that he had given Under no circumstances, he had told the robot, must it obey any further commands of his until he was safely inside diaspar. Those were the orders. I they were obeyed, alvin had placed his fate beyond the reach of human interference. Never hesitating, the machine raced on along the path he had so carefully mapped out for it. A part of him was still pleading angrily to be released, but he knew now that he was safe. And presently seranis understood that too, for the forces inside his brain ceased to war with one another. O more he was at peace, as ages ago an earlier wanderer had been when, lashed the mast of his ship, he had heard the song of the sirens die away across wine-dark sea. Fifteen alvin did not relax until the chamber of the moving ways was around him once more. There had still been the danger that the peo of lys might be able to stop, or even to re•verse, the vehicle in which he traveling, and bring him back helplessly to his starting point. But his retur was an uneventful repetition of the outward trip; forty minutes after he had left lys he was in the tomb of yarlan zey. The servants of the council wer waiting for him, dressed in the formal black robes which they had not worn centuries. Alvin felt no surprise, and little alarm, at the presence of this reception commitee. He had now overcome so many obstacles that one more made little difference. He had learned a great deal since leaving diaspar, and wit that knowledge had come a confidence verging upon arrog•ance. Moreover, he now had a powerful, if erratic, ally. The best minds of lys had been unable to interfere with his plans; somehow, he believed that diaspar could do no
better. There were rational grounds for this belief, but it was based partly upon something beyond reason-a faith in his destiny which had slowly been growing in alvin's mind. The mystery of his origin, his success in doing wha no earlier man had ever done, the way in which new vistas had opened up be him, and the manner in which obstacles had failed to halt him-all these thin added to his self-confidence. Faith in one's own destiny was among the most valuable of the gifts which the gods could bestow upon a man, but alvin did not know how many it had led to utter disaster. "Alvin," said the leader of the city's proctors, "we have orders to accompany you wherever you go, until the council has heard your case and rendered its verdict. "With what offense am i charged?" asked alvin. He was still exhilarated by the excitement and elation of his escape from lys and could not yet take this new development very seriously. Presumably khedron had talked; he felt a brief annoyance at
the jester for betraying his secret. "No charge has been made," came the reply. "If neces•sary, one will be framed after you have been heard." "and when will that be?" "very soon, i imagine." the proctor was obviously ill at ease and was not sure how to handle his unwelcome assignment. At one moment would treat alvin as a fellow citizen, and then he would remember his duties as a custodian and would adopt an attitude of exaggerated aloofness. "This robot," he said abruptly, pointing to alvin's com•panion, "where did it come from? Is it one of ours?" "no," replied alvin. "I found it in lys, the cou i have been to. I have brought it here to meet the central computer." this calm statement produced a considerable commotion. The fact that there was something outside diaspar was hard enough to accept, but that alvin should
have brought back one of its inhabitants and proposed to introduce it to the brain of the city was even worse. The proctors looked at each other with su helpless alarm that alvin could hardly refrain from laughing at them. As they walked back through the park, his escort keeping discreetly at the rear and talking among itself in agitated whispers, alvin considered his next move. The first thing he must do was to discover exactly what had happened during his absence. Khedron, seranis had told him, had vanished. There were countless places where a man could hide in di•aspar, and since the jester's knowledge the city was un•surpassed it was not likely that he would be found until be chose to reappear. Perhaps, thought alvin, he could leave a message where

khedron would be bound to see it, and arrange a rendezvous. However, the presence of his guard might make that impossible. He had to admit that the surveillance was very discreet. By the time he had reached his apartment, he had almost for•gotten the existence of the proctors. He imagined that they would not interfere with his movements unless he attempted to leave diaspar, and for the time being he had no intention of doing that. Indeed, he was fairly certain that it would be impossible to return to lys by his orginal route. By this time, surely, the underground carrier system would have been
put out of action by seranis and her colleagues. The proctors did not follow him into his room; they knew that there was only the one exit, and statione themselves outside that. Having had no instructions regarding the robot, they let it accompany alvin. It was not a machine which they had any desire to interfere with, since its alien con•struction was obvious. From its behavior they could not tell whether it was a passive servant of alvin's or whether was operating under its own volition. In view of this un•certainty, they were quite content to leave it severely alone. Once the wall had sealed itself behind him, alvin ma•terialized his favorite divan and threw himself down upon it. Luxuriating in his familiar surroundings, he called out of the memory
units his last efforts in painting and sculpture, and examined them with a critical eye. If they had failed to satisfy him before, they were doubly displeasing now, and he could take no further pride in them. The person who had created them no longer existed; into the few days he had been away from diaspar, it seemed to alvin that he had crowded the experience of a lifetime He canceled all these products of his adolescence, erasing them forever and
not merely returning them to the memory banks. The room was empty again, apa from the couch on which he was reclining, and the robot that still watched with wide, unfathomable eyes. What did the robot think of diaspar? Wondered alvin. Then he remembered that it was no stranger here, for it had known th city in the last days of its contact with the stars. Not until he felt thoroughly at home once more did alvin begin to call his friends. He began with eriston and etania, though out of the sense of duty rather than any re desire to see and speak to them again. He was not sorry when their communicators informed him that they were unavail•able, but he left them both
a brief message announcing his return. This was quite unnecessary, since by
now the whole city would know that he was back. However, he hoped that they would appreciate his thoughtfulness; he was beginning to learn consideration, though he had not yet realized that, like most virtues, it had little merit unless it was sponta•neous and unself-conscious. Then acting on a sudden impulse, be called the number that khedron had given him so long ago in the tower of loranne. He did not, of course, expect an answer, but there was always the possiility that khedron had left a message. His guess was correct; but the message itself was shatteringly unexpected. The wall dissolved, and khedron was standing before him. The jester looked tired and nervous, no
longer the confi•dent, slightly cynical person who had set alvin on the path that led to lys. There was a haunted look in his eyes, and he spoke as th he had very little time. "Alvin," he began, "this is a recording. Only you receive it, but you can make what use of it you wish. It will not matter me. "When i got back to the tomb of yarlan zey, i found that alystra had following us. She must have told the coun•cil that you had left diaspar, and that i had helped you. Very soon the proctors were looking for me, and i decided to go into hiding. I am used to that-i have done it before when so of my jests failed to be appreciated." (there, thought alvin, was a flash of the old khedron.) "they could not have found me in a thousand years-but someone else nearly did. There are strangers in diaspar, alvin; they could
only have come from lys, and they are looking for me. I do not know what means, and i do not like it. The fact that they nearly caught me, though t are in a city that must be strange to them suggests that they possess telepathic powers. I could fight the council, but this is an unknown peril which i do not care to face. "I am therefore anticipating a step which i t the coun•cil might well force upon me, since it has been threatened before.

am going where no one can follow, and where i shall escape whatever changes are now about to happen to diaspar. Perhaps i am foolish to do this; that something which only time can prove. I shall know the answer one day "by no you will have guessed that i have gone back into the hall of creation, into the safety of the memory banks. Whatever happens, i put my trust in the central computer and the forces it controls for the benefit of diaspar. If any•thing tampers with the central computer, we are all lost. If not, i have nothing to fear. "To me, only a moment will seem to pass before i walk for into diaspar again, fifty or a hundred thousand years from now. I wonder wha sort of city i shall find? It will be strange if you are there; some day, suppose, we will meet again. I cannot say whether i look forward to that meet•ing or fear it. "I have never understood you, alvin, though there was a time when i was vain enough to think i did. Only the central computer knows the truth, as it knows the truth about all those other uniques who have appeared from time to time down the ages and then were seen no more. Have dis•covered what happened to them?" "one reason, i suppose, why i am escaping into the future is because i am impatient. I want to see the results of wh you have started, but i am anxious to miss the intermediate stages-which i suspect may be unpleasant. It will be in•teresting to see, in that world whi will be around me in only a few minutes of apparent time from now, whether are remembered as a creator or as a destroyer-or whether , you are remembere at all." "good-bye, alvin. I had thought of giving you some ad•vice, but i not suppose you would take it. You will go your own way, as you always hav and your friends will be tools to use or discard as occasion suits." "that all. I can think of nothing more to say." for a moment khedron-the khedron
no longer ex isted save as a pattern of electric charges in the memo cells of the city-looked at alvin with resignation and, it seemed, with sadness. Then the screen was blank again. Alvin remained motionless for a lon time after the image, of khedron had faded. He was searching his soul as he had seldom done before in all his life, for he could not deny the truth of much that khedron had said. When had he paused ; in all his schemes and adventures, to consider the effect of what he was doing upon any of his friends? He had brought anxiety to them and might soon bring worse-all becaus of his insatiable curiosity and the urge to discover what should not be know He had never been fond of khedron; the jester's astrin•gent personality prevented any close relationship, even if alvin had desired it. Yet now, as thought of khedron's parting words, he was shaken with remorse. Because of hi actions, the jester had fled from this age into the unknown future. But surely, thought alvin, he had no need to blame him•self for that. It proved only what he had already known-that khedron was a coward. Perhaps he was no more of a coward than anyone else in diaspar, he had the additional misfor•tune of possessing a powerful imagination. Alvin could ac•cept some responsibility for his fate, but by no means all. Who else in diaspar had h harmed or distressed? He thought of jeserac, his tutor, who had been patient with what must have been his most difficult pupil. He remembered all the little kindnesses that his parents had shown him over the years, now that he looked back upon them, there were more than he had imagined. And he thought alystra. She had loved him, and he had taken that love or ignored it as he chose. Yet what else was he to have done? Would she have been any happier
he spurned her completely? He understood now why he had never loved alystra, or any of the women he had known in diaspar. That was another lesson that had taught him. Diaspar had forgotten many things, and among them was the tr meaning of love. In airlee he had watched the mothers dandling their children on their knees, and had himself felt that protective tender•ness for all smal and helpless creatures that is love's unselfish twin. Yet now there was no woman in diaspar who knew or cared for what had once been the final aim of love. There were no real emotions, no deep passions, in the im•mortal city. Perhaps such things only thrived because of their very transience, because
they could not last. Forever and lay always under the shadow which diaspar h banished. That was the moment, if such a moment ever existed, when alvin

realized what his destiny must be. Until now he had been the unconscious age of his own impulses. If he could have known so archaic an analogy, he might have compared himself to a rider on a runaway horse. It had taken him to m strange places, and might do so again, but in its wild galloping it had sho him its powers and taught him where he really wished to go. Alvin's reverie was rudely interrupted by the chimes of the wall screen. The timbre of the sound told him at once that this was no incoming call, but that someone had arrived to see him. He gave the admission signal, and a moment later was facing jeserac. His tutor looked grave, but not unfriendly. "I have been aske to take you to the council, alvin," he said. "It is waiting to hear you." jeserac saw the robot and examined it curiously. "So this is the companion y have brought back from your travels. I think it had better come with us." t suited alvin very well. The robot had already ex•tricated him from one dangerous situation, and he might have to call upon it again. He wondered wh the machine had thought about the adventures and vicissitudes in which he had involved it, and wished for- the thousandth time that he could understand wha was going on inside its closely shuttered mind. Alvin had the impression that for the moment it had decided to watch, analyze, and draw its own conclu•sio doing nothing of its own volition until it had judged the time was ripe. Th perhaps quite suddenly, it might decide to act; and what it chose to do mig not suit alvin's plans. The only ally he possessed was bound to him by the most tenuous ties of self interest and might desert him at any moment. Alyst was waiting for them on the ramp that led out into the street. Even if alv had wished to blame her for what•ever part she had played in revealing his secret, he did not have the heart to do so. Her distress was too obvious, her eyes brimmed with tears as she ran up to greet him. "Oh, alvin!" she cried. "What are they going to do with you?" alvin took her hands in his w a tenderness that sur•prised them both. "Don't worry, alystra," he said. "Everything is going to be all right. After all, at the very worst the coun can only send me back to the memory banks-and somehow i don't think that wi happen." her beauty and her unhappiness were so appealing that, even now,
alvin felt his body responding to her presence after its old fashion. But it was the lure of the body alone; he did not disdain it, but it was no long enough. Gently he disengaged his hands and turned to follow jeserac toward th council chamber. Alystra's heart was lonely, but no longer bitter, as she watched him go. She knew now that she had not lost him, for he had never belonged to her. And with the acceptance of that knowledge, she had begun to put herself beyond the power of vain regrets. Alvin scarcely noticed the curious or horrified glances of his fellow citizens as he and his retinue ma their way through the familiar streets. He was marshaling the argu•ments he might have to use, and arranging his story in theform most favorable to himself. From time to time he as•sured himself that he was not in the least alarmed and thathe was still master of the situation. They waited only a few minutes in the anteroom, but it was long enough for alvin to wonder why, if was unafraid, his legs felt so curiously weak. He had known this sensation before when be had forced himself up the last slopes of that distant hill i lys, where hilvar had shown him the waterfall from whose summit they had see the explosion of light that'had drawn them to shalmirane. He wondered what hilvar was doing now, and if they would ever meet again. It was suddenly ve important to him that they should. The great doors dilated, and he followed jeserac into the council chamber. The twenty members were already seated
around their crescent-shaped table, and alvin felt flattered as he noticed that there were no empty places. This must be the first time for many centuries that the entire council had been gathered together without a single abstention. Its rare meetings were usually a complete formality, all ordinary business being dealt with by a few visiphone calls and, if necessary, an interview betwen the president and the cen•tral computer. Alvin knew by sight most of the members of the council, and felt reassured by the presence of s many familiar faces. Like jeserac, they did not seem unfriendly-merely anxious and puzzled. They were, after all, reasonable men. They might be annoyed that

someone had proved them wrong, but alvin did not believe that they would bea him any resentment. Once this would have been a very rash assump•tion, but human nature had improved in some respects. Tey would give him a fair hearin but what they thought was not all-important. His judge now would not be the coun•cil. It would be the central computer. Sixteen There were no formalities. The president declared the meeting open and then turned to alvin. "Alvin," he said, kindly enough, "we would like you to tell us what has happened to you since you disappeared ten days ago." the use of the word "disappeared," thought alvin, was highly significant. Even now, the council
was reluctant to admit that he had really gone outside diaspar. He won•dered if they knew that there had been strangers in the city, and rather doubted
In that event they would have shown considerably more alarm. He told his sto clearly and without any dramatics. It was strange and unbelievable enough to their ears, and needed no embellishment. Only at one place did he depart fro strict accuracy, for he said nothing about the manner of his escape from lys It seemed more than likely that he might want to use the same method again. was fascinating to watch the way in which the attitude of the council member altered during the course of his narrative. At first they were skeptical, refusing to accept the denial of ail they had believed, the violation of the deepest prejudices when alvin told them of his passionate desire to explore
the world beyond the city, and his irra•tional conviction that such a world did exist, they stared at him as if he was some strange and incomprehensible animal. To their minds, indeed, he was but finally they were com•pelled to admit that he had been right, and that they had been mistaken. As alvin's story unfolded, any doubts they may have had slowly dissolved. They might not like what he had told them, but they could no longer deny its truth. If th felt tempted to do so, they had only to look at alvin's silent companion. There was only one aspect of his tale that roused their indignation-and then it was not directed toward him. A buzz of annoyance went around the chamber alvin explained the anxiety of lys -to avoid contamination with diaspar, and the steps that seranis had taken to prevent such a catas•trophe. The city wa proud of its culture, and with good reason. That anyone should regard them a inferiors was more than the council members could tolerate. Alvin was very careful not to give offense in anything he said; he wanted, as far as possible, to win the council to his side. Throughout, he tried to give the impression that he had seen nothing wrong in what he had done, and that he expected praise rather than censure for his discoveries. It was the best
policy he could have adopted, for it disarmed most of his would-be critics i advance. It also had the effect -though he had not intended this-of transferring any blame to the vanished khedron. Alvin himself, it was clear t his listeners, was too young to see any danger in what he was doing. The jester, however, should certainly have known better and had acted in a thoroughly irresponsible fashion. They did not yet know how fully khedron himself had agreed with them. Jeserac, as alvin's tutor, was also deserving o some cen•sure, and from time to time several of the councilors gave him thoughtful glances. He did not seem to mind, though he was perfectly well aware of what they were thinking. There was a certain honor in having instructed the most original mind that had come into diaspar since the dawn ages, and nothing could rob jeserac of that. Not until alvin had finished th factual account of his adventures did be attempt a little persuasion. Somehow, he would have to convince these men of the truths that he had learned in l but now how could he make them really understand something that they had nev seen and could hardly imagine? "It seems a great tragedy," he said, "that th two sur•viving branches of the human race should have become separated for
such an enormous period of time. One day, perhaps, we may know how it happened, but it is more im•portant now to repair the break-to prevent it happening again. When i was in lys i protested against their view that they were superior to us; they may have much to teach us, but we also have much teach them. If we both believe that we have nothing to learn from the other is it not obvious that we will both be wrong?" he looked expectantly along

line of faces, and was encouraged to go on. "Our ancestors," he continued, "built an empire that reached to the stars. Men came and went at will among all those worlds-and now their descendants are afraid to stir beyond the wall of their city. Shall 1 tell you why?" he paused; there was no movement at
in the great, bare room. "It is because we are afraid-afraid of something th happened at the beginning of history. I was told the truth in lys, though i guessed it long ago. Must we always hide like cowards in diaspar, pretending that nothing else exists -because a billion years ago the invaders drove us back to earth?" he had put his finger on their secret fear-the fear that he had never shared and whose power he could therefore never fully understand.
Now let them do what they pleased; he had spoken the truth as he saw it. president looked at him gravely. "Have you anything more to say," he asked, "before we consider what is to be done?" only one thing. I would like to t this robot to the central computer." "but why? You know that the computer is already aware of everything that has happened in this room." ` i still wish go," replied alvin politely but stubbornly. "I ask permission both of the council and the computer." before the president could reply, a clear, calm voice sounded through the chamber. Alvin had never heard it be•fore in his life, but he knew what it was that spoke. The information machines, which we no more than outlying fragments of this great intelligence, could speak to me
•but they did not possess this unmistakable accent of wisdom and authority. "Let him come to me," said the central computer. Alvin looked at the president. It was to his credit that he did not attempt to exploit his victory. He merely asked, "have i your permission to leave?" the president looked around the council chamber, saw no disagreement there, and replied a little helplessly: "very well. The proctors will accompany you, and will bring you back here when we have finished our discussion." alvin gave a slight bow of thanks, the great doors ex•panded before him, and he walked slowly out of the cham•ber. Jeserac had accompanied him, and when the doors had closed once more, he turned to face his tutor. "What do you think the council will now?" he asked anxiously. Jeserac smiled. "Impatient as ever, aren't you?" he said. "I do not know what my guess is worth, but i imagine that they will decide to seal the tomb of yarlan zey so that no one can ever again make journey. Then diaspar can continue as before." "that is what i am afraid of, said alvin bitterly. "And you still hope to prevent it?" alvin did not at o reply; he knew that jeserac had read his intentions, but at least his tutor could not foresee his plans, for he had none. He had come to the stage whe could only improvise and meet each new situation as it arose. "Do you blame me?" he said presently, and jeserac was surprised by the new note in his voice. It was a hint of humility, the barest suggestion that for the first time al•vin sought the approval of his fellow men. Jeserac was touched by it but he was too wise to take it very seriously. Alvin was under a considerab strain, and it would be un•safe to assume that any improvement in his character was permanent. "That is a very hard question to answer," said
jeserac slowly. "I am tempted to say that all knowledge is valuable, and it cannot be denied that you have added much to our knowledge. But you have al added to our dangers, and in the long run which will be more important? How often have you stopped to consider that?" for a moment master and pupil regarded each other pen•sively, each perhaps seeing the other's point of view more clearly than ever before in his life. Then, with one impulse, they turn together down the long passage from the coun•cil chamber, with their escort still following patiently in the rear. This world, alvin knew, had not been made for man. Un•der the glare of the fierce blue lights-so dazzling that th pained the eyes-the long, broad corridors seemed to stretch to infinity. Down these great passageways, the robots of diaspar must come and go throughout their endless lives, yet not once in centuries did they echo to the sound o hu•man feet. Here was the underground city, the city of machines without whic diaspar could not exist. A few hundred yards ahead, the corridor would open into a circular chamber more than a mile across, its roof supported by great columns that must also bear the unimaginable weight of power center. Here,

according to the maps, the central computer brooded eternally over the fate o diaspar. The chamber was there, and it was even vaster than alvin had dared imagine but where was the computer? Somehow he had expected to meet a single huge machine, naive though he knew that this conception was. The tremendous
but mean•ingless panorama beneath him made him pause in wonder and
uncertainty. The corridor along which they had come ended high in the wall o the chamber-surely the largest cavity ever built by man-and on either side
long ramps swept down to the distant floor. Covering the whole of that brilliantly lit ex•panse were hundreds of great white structures, so
unex•pected that for a moment alvin thought he must be look•ing down upon a subterranean city. The impression was star•tlingly vivid, and it was one that he never wholly lost. No•where at all was the sight he had expected-the familiar gleam of metal which since the beginning of time man had learned to associate with his servants. Here was the end of an evolution almost as long as man's. Its beginnings were lost in the mists of the dawn ages, when humanity had first learned the use of power and sent its noisy engines clanking about the world. Steam, water, wind-all had been harnessed for a little while and then abandoned. For centuries the energy of matter had run the world until it too had been superseded, and with each change the old machines were forgotten and new ones took their place. Very slowly, over thousands of years, the ideal of the perfect machine was approached-that ideal which had once been a dream, then a distant prospect, and at last reality: machine may contain any moving parts. Here was the ultimate expression of that ideal. Its achieve•ment had taken man perhaps a hundred million years,
and in the moment of his triumph he had turned his back upon the machine forever. It had reached finality, and thenceforth could sustain itself eternally while serving him. Alvin no longer asked himself which of these silent white presences was the central computer. He knew that it com•prised them all-and that it extended far beyond this cham•ber, including within its being all the countless other ma•chines in diaspar, whether they were mobile
or motionless. As his own brain was the sum of many billion separate cells, arrayed throughout a volume of space a few inches across, so the physical elements of the central computer were scat•tered throughout the length and breadth of diaspar. This chamber might hold no more than the switching system whereby all these dispersed units kept in touch with one an•other. Uncertain where to go next, alvin stared down the great sweeping ramps and across the silent arena. The central com•puter must know that he was here, as it knew everything that was happening in diaspar. He could only wait for its in•structions. The now-familiar yet still awe-inspiring voice was so quiet and so close to him that he did not believe that his escort could also hear it "Go down the left-hand ramp," it said. "I will direct you from there." he walked slowly down the slope, the robot floating above him. Neither jeserac
nor the proctors followed; he wondered if they had received orders to remain here, or whether they had decided that they could supervise him just as well from their vantage point without the bother of making this long descent. Or perhaps they had come as close to the central shrine of diaspar as they car to approach. At the foot of the ramp, the quiet voice redirected alvin, and walked between an avenue of sleeping titan shapes. Three times the voice spok to him again, until presently he knew that he had reached his goal. The machine before which he was standing was smaller than most of its companions, but he felt dwarfed as he stood beneath it. The five tiers with their sweep horizontal lines gave the impression of some crouching beast, and looking from it to his own robot alvin found it hard to believe that both were products the same evolution, and both described by the same word. About three feet fr the ground a wide transparent panel ran the whole length of the structure. Alvin pressed his fore•head agaipst the smooth, curiously warm material and peered into the machine. At first he saw nothing then, by shielding his eyes he could distinguish thousands of faint points of light hanging in
nothingness. They were ranged one beyond the other in a three-dimensional lattice, as strange and as meaningless to him as the stars must have been t

ancient man. Though he watched for many minutes, forgetful of the passage of time, the colored lights never moved from their places and their brilliance never changed. If he could look into his own brain, alvin realized, it would mean as little to him. The machine seemed inert and mo•tionless because he could not see its thoughts. For the first time, he began to have some dim understand•ing of the powers and forces that sustained the city. All his life he had accepted without question the miracle of the synthesizers which age after age provided in an unending stream all the needs of diaspar. Thousands of times he had watched that act of creation, seldom remembering that some•where must exist the prototype of that which he had seen come into the world. As a human mind may dwell for a little while upon a single thought, the infinitely greater brains which were but a portion of the central compute could grasp and hold for•ever the most intricate ideas. The patterns of all created things were frozen in these eternal minds, needing only the touch of human will to make them reality. The world had indeed gone far since, hour upon hour, the first cavemen had patiently chipped their arrowheads and knives from the stubborn stone. Alvin waited, not caring to speak until he had received some further sign of recognition. He wondered how the cen•tral
computer was aware of his presence, and could see him and hear his voice. Nowhere were there any signs of sense organs-none of the grilles or screens emotionless crystal eyes through which robots normally had knowledge of the world around them. "State your problem," said the quiet voice in his ear. It seemed strange that this overwhelming expanse of machinery should sum up its thoughts so softly. Then allvin realized that he was flattering himself;
perhaps not even a millionth part of the central computer's brain was dealing with him. He was just one of the innumerable incidents that came to its simultaneous attention as it watched over diaspar. It was hard to talk to a presence who filled the whole of the space around you. Alvin's words seemed die in the empty air as soon as he had uttered them. "What am i?" he aske he had put that question to one of the information ma•chines in the city, h knew what the reply would have been. Indeed, he had often done so, and they had always answered, "you are a man." but now he was dealing with an intelligence of an altogether different order, and there was no need for painstaking semantic accuracy. The central computer would know what he meant, but that did not mean that it would answer him. Indeed, the reply was exact what alvin had feared. "I cannot answer that question. To do so would be to re•veal the purpose of my builders, and hence to nullify it." "then my role was planned when the city was laid down?" "that can be said of all men." t reply made alvin pause it was true enough; the human inhabitants of diaspar had been designed as care- fully as its machines. The fact that he was a unique gave alvin rarity, but there was no necessary virtue in that. He knew that he could learn nothing further here regarding the mystery of his origin. It was useless to try to trick this vast intelligence, or to hope that it would disclose information it had been ordered to conceal. Alvin was not
unduly dis•appointed; he felt that he had already begun to glimpse the truth, and in any case this was not the main purpose of his visit. He looked at robot he had brought from lys, and wondered bow to make his next step. It might react violently if it knew what he was planning, so it was essential that it should not overhear what he intended to say to the central computer. "Can you arrange a zone of silence?" he asked. Instantly, be sensed the unmistakable "dead" feeling, the total blanketing of all sounds, which
descended when one was inside such a zone. The voice of the computer, now curiously flat and sinister, spoke to him: "no one can hear us now. Say wha you wish." alvin glanced at the robot; it bad not moved from its po•sition. Perhaps it suspected nothing, and he had been quite wrong in ever imagining that it had plans of its own. It might have followed him into diaspar like faithful, trusting serv•ant, in which case what he was planning now seemed a partic•ularly churlish trick. "You have heard bow i met this robot," alvin

about the other worlds than earth, since it fol•lowed the master on his travels. Unfortunately, its speech circuits are blocked. I do not know how effective that block is, but i am asking you to clear it." his voice sounde dead and hollow as the zone of silence absorbed every word before it could form an echo. He waited, within that invisible and unreverberant void, for hi request to be obeyed or rejected. "Your order involves two problems," replied the com•puter. "One is moral, one technical. This robot was designed to obey the orders of a certain man. What right have i to override them, even if i can?" it was a question which alvin had anticipated and for which he had prepared several answers. "We do not know what exact form the master's prohi•bition took," be replied. "If you can talk to the robot, you may be a to persuade it that the circumstances in which the block was imposed have no changed." it was, of course, the obvious approach. Alvin had attempted it himself, without success, but he hoped that the central computer, with its infinitely greater mental resources, might accomplish what he had failed to
do. "That depends entirely upon the nature of the block," came the reply. "I is possible to set up a block which, if tampered with, will cause the conte of the memory cells to be erased. However, i think it unlikely that the mas possessed suf•ficient skill to do that; it requires somewhat specialized techniques. I will ask your machine if an erasing circuit has been set up i its memory units." "but suppose," said alvin in sudden alarm, "it causes erasure of memory merely to ask if an erasing circuit exists?" "there is a standard procedure for such cases, which i shall follow. I shall set up secondary instructions, telling the ma•chine to ignore my question if such a situation exists. It is then simple to insure that it will become involved i a logical paradox, so that whether it answers me or whether it says nothing will be forced to disobey its' instructions. In such. An event all robots ac in the same manner, for their own protection. They clear their input circuits and act as if no question has been asked." alvin felt rather sorry that he raised the point, and after a moment's mental struggle decided that he too would adopt the same tactics and pretend that he had never been asked the question. At least he was reassured on one point•the central computer was
fully prepared to deal with any booby traps that might exist in the robot's memory units. Alvin had no wish to see the machine reduced to a pile of ju rather than that, he would willingly return it to shalmirane with its secrets still intact. He waited with what patience he could while the silent, impalpable meeting of two intellects took place. Here was an encounter between two minds, both of them created by hu•man genius in the long-lost golden age of its greatest achieve•ment. And now both were beyond the full understanding of any living man. Many minutes later, the hollow, anechoic voice of the central computer spoke again. "I have established partial contact," it said.
"At least i know the nature of the block, and i think i know why it was imposed. There is only one way in which it can be broken. Not until the gr ones come to earth will this robot speak again." "but that is nonsense!" protested alvin. "The master's other disciple believed in them, too, and tried to expain what they were like to us. Most of the time it was talking gibberish. The great ones never existed, and never will exist." it seemed a complete impasse, and alvin felt a sense of bitter, helpless disappointment.
He was barred from the truth by the wishes of a man who had been insane, who had died a billion years ago. "You may be correct," said the central computer, "in saying that the great ones never existed. But that does not me that they never will exist." there was another long silence while alvin considered the meaning of this remark, and while the mind of the two robots made their delicate contact again. And then, with•out any warning, he was in shalmirane. Seventeen It was just as he had last seen it, the great ebon bowl drinking the sunlight and reflecting none back to the eye. He stood amo the ruins of the fortress, looking out across the lake, whose motionless
waters showed that the giant polyp was now a dispersed cloud of animalcules and no longer an organized, sentient being. The robot was still beside him, but of hilvar there was no sign. He had no time to wonder what that meant,

to worry about his friend's absence, for almost at once there occurred something so fantastic that all other thoughts were banished from his mind.
The sky began to crack in two. A thin wedge of darkness reached from horizo to zenith, and slowly widened as if night and chaos were breaking in upon t universe. Inex•orably the wedge expanded until it embraced a quarter of the sky. For all his knowledge of the real facts of astronomy, alvin could not fight against the overwhelming impression that he and his world lay beneath a great blue dome-and that something was now breaking through that dome from outside. The wedge of night had ceased to grow. The powers that had made it were peering down into the toy universe they had discovered, perhaps
conferring among themselves as to whether it was worth their attention. Underneath that cosmic scrutiny, alvin felt no alarm, no terror. He knew that he was face to face with power and wisdom, before which a man might feel a but never fear. And now they had decided-they would waste some frag•ments of eternity upon earth and its peoples. They were coming through the window they had broken in the sky. Like sparks from some celestial forge, they drifted down to earth. Thicker and thicker they came, until a waterfall of fire was streaming down from heaven and splashing in pools of liquid light as it reached the ground. Alvin did not need the words that sounded in his ears l a benediction: "the great ones have come." the fire reached him, and it did not burn. It was every•where, filling the great bowl of shalmirane with its golden glow. As he watched in wonder, alvin saw that it was not a featurele flood of light, but that it had form and structure. It began to resolve its into distinct shapes, to gather into separate fiery whirlpools. The whirlpools spun more and more swiftly on their axes, their centers rising to form colum within which alvin could glimpse mysterious evanescent shapes. From these
glowing totem poles games a faint musical note, infinitely distant and hauntingly sweet. "The great ones have come." this time there was a reply. A alvin heard the words: "the servants of the master greet you. We have been wait•ing for your coming," he knew that the barriers were down. And in that moment, shalmirane and its strange visitors were gone, and he was standing
once more before the central computer in the depths of diaspar. It had all been illusion, no more real than the fantasy world of the sagas in which he had spent so many of the hours of his youth. But how had it been created; whence had come the strange images he had seen? "It was an unusual problem," said the quiet voice of the central computer. "I knew that the robot must h some visual conception of the great ones in its mind. If i could convince i that the sense impressions it received coincided with that image, the rest would be simple:" "and how did you do that?" "basically, by asking the robot what the great ones were like, and then seizing the pattern it formed in it thoughts. The pattern was very incomplete, and i had to improvise a good dea Once or twice the picture i created began to de•part badly from the robot's conception, but when that hap•pened i could sense the machine's growing perplexity and modify the image before it became suspicious. You will ap•preciate that i could employ hundreds of circuits where it could employ
only one, and switch from one image to the other so quickly that the change could not be perceived. It was a kind of conjuring trick; i was able to saturate the robot's sensory circuits and also to overwhelm its critical faculties. What you saw was only the final, corrected image-the one which bes fitted the master's revelation. It was crude, but it sufficed. The robot was convinced of its genuineness long enough for the block to be lifted, and in that moment i was able to make complete contact with its mind. It is no lo insane; it will answer any questions you wish." alvin was still in a daze; afterglow of that spurious apocalypse still burned in his mind, and he did n pretend fully to understand the central computer's explanation. No matter; a miracle of therapy had been accomplished, and the doors of knowledge had been flung open for him to enter. Then he remembered the warning that the central com•puter had given him, and asked anxiously: "what about the moral objections

will see that

he

claimed to have produced many

miracles. His disciples

believed him,

and

their conviction added to his

power. But, of course, all

those miracles had some simple explan•ation-when indeed they occurred at all.
I find it surprising that otherwise intelligent men should have let themselves be deceived in such a manner." "so the master was a fraud?" "no; it is not simple as that. If he had been a mere impostor, he would never have achieve such success, and his movement would not have lasted so long. He was a good man, and much of what he taught was true and wise. In the end, he believed his own miracles, but he knew that there was one witness who could refute them. The robot knew all his secrets; it was his mouthpiece and his colleagu yet if it were ever questioned too closely it could destroy the foun•dations of his power. So he ordered it never to reveal its memories until the last of the universe, when the great ones would come. It is hard to believe that such a mixture of deception and sincerity could exist in the same man, but such was the case." alvin wondered what the robot felt about this escape fro its ancient bondage. It was, surely, a sufficiently com•plex machine to understand such emotions as resentment. It might be angry with the master for having enslaved it -and equally angry with alvin and the central computer for having tricked it back into sanity. The zone of silence had been lifted; the was no further need for secrecy. The moment for which alvin had been waiting had come at last. He turned to the robot, and asked it the question that h haunted him ever since he had heard the story of the master's saga. And the robot replied. Jeserac and the proctors were still waiting patiently when he rejoined them. At the top of the ramp, before they en•tered the corridor, alvin looked back across the cave, and the illusion was stronger than ever. Lying beneath him was a dead city of strange white buildings, a city bleache by a fierce light not meant for human eyes. Dead it might be, for it had lived, but it pulsed with energies more potent than any that had ever quickened organic matter. While the world endured, these silent machines would still be here, never turning their minds from the thoughts that men of geniu had given them long ago. Though jeserac tried to question alvin on the way back to the council chamber, he learned nothing of his talk withthe central computer. This was not merely discretion on alvin's part; he was still too much lost in the wonder of what he had seen, too intoxicated with success, any coherent conversation. Jeserac had to muster what patience he couldand
hope that presently alvin would emerge from his trance. The streets of diaspa were bathed with a light that seemed pale and wan after the glare of the machine city. But alvin scarcely saw them; he had no regard for the familiar beauty of the great towers drifting past him, or the curious glances of his fellow citizens. It was strange, he thought, how every•thing that had happened to him led up to this moment. Since he had met khedron, events seemed to h moved automat•ically toward a preetermined goal. The
monitors-lys-•shalmirane-at every stage he might have turned aside with unseeing eyes, but something had led him on. Was he the maker of his own destiny, or was he especially favored by fate? Perhaps it was merely a matte of probabilities, of the operation of the laws of chance. Any man might have found the path his footsteps had traced, and countless times in the past age others must have gone almost as far. Those earlier uniques, for example-what had happened to them? Perhaps he was merely the first to be lucky. All the back through the streets, alvin was estab•lishing closer and closer rapport
with the machine he had released from its age-long thralldom. It had always been able to receive his thoughts, but previously he had never known whether it would obey any orders he gave it. Now that uncertainty was gone; he coul talk to it as he would to another human being, though since he was not alo he directed it not to use verbal speech but such simple thoughtimages as he could understand. He sometimes resented the fact that robots could talk freely to one another on the tele• pathic level, whereas man could not -except in lys. Herewas another power that diaspar had lost or deliberately set aside. H continued the silent but somewhat one-sided conver•sation while they were
waiting in the anteroom of the coun•cil chamber. It was impossible not to

compare his present situation with that in lys, when seranis and her colleagues had tried to bend him to their wills. He hoped that there would
no need for another conflict, but if one should arise he was now far better prepared for it. His first glance at the faces of the council members told alvin what their decision had been. He was neither surprised nor particularly disappointed, and he showed none of the emotion the councilors might have expected as he listened to the president's summing-up. "Alvin," began the president, "we have considered with great care the situation which your discovery has brought about, and we have reached this unanimous decision. Be•cause no one wishes any change in our way of life, and because only once many millions of years is anyone born who is capable of leaving diaspar even if the means exists, the tunnel system to lys is unnecessary and may well b danger. The entrance to the chamber of the moving ways has therefore been sealed. "Moreover, since it is possible that there may be other ways of leaving the city, a search will be made of the monitor memory units. That search has already begun." "we have also considered what action, if any, need be taken with regard to you. In view of your youth, and the peculiar circumstances of your origin, it is felt that you can•not be censured for wh you have done. Indeed, by dis•closing a potential danger to our way of life, you have done the city a service, and we record our appreciation of that fact." there was a murmur of applause, and expressions of sat•isfaction spread across the faces of the councilors. A diffi•cult situation had been speedily dealt with, they had avoided the necessity of reprimanding alvin, and now the could go their ways again feeling that they, the chief citizens of dias•par, had done their duty. With reasonably good fortune, it might be centuries
before the need arose again. The president looked expectantly at alvin;
perhaps be hoped that alvin would reciprocate and express his appre•ciation of the council for letting him off so lightly. He was disappointed. "May i ask one question?" said alvin politely. "Of course." "the central computer, i take it, approved of your ac•tion?" in the ordinary way, this would have been an impertinent question to ask. The council was not supposed to justify its decisions or explain how it had arrived at them. But alvin himself had been taken into the confidence of the central computer, for some strange reason of its own. He was in a privileged position. The question clearly caused some embarrassment, and the reply came rather reluctantly. "Naturally we consulted with the central computer. It told us to use our own judgment." alvin had expected as much. The central computer would have been conferring with the council at the same moment as it was talking to him-at the same moment, in fact, as it was attending to a million other tasks in diaspar. It knew, as alvin, that any decision the council now made was of no importance. The futu had passed utterly beyond its control at the very moment when, in happy ignor•ance, it had decided that the crisis had been safely dealt with. Alvin felt no sense of superiority, none of the sweet an•ticipation of impending triumph, as he looked at these foolish old men who thought themselves the rulers of diaspar. He had seen the real ruler of the city, and had spoken
it in the grave silence of its brilliant, buried world. That was an en•count which had burned most of the arrogance out of his soul, but enough was left for a final venture that would surpass all that had gone before. As he took leave of the council, he wondered if they were surprised at his quiet acquiescence, his lack of indignation at the closing of the path to lys. The proctors did not ac•company him; he was no longer under observation, at least in so open a manner. Only jeserac followed him out of the council chamber a into the colored, crowded streets. "Well, alvin," he said. "You were on your best behavior, but you cannot deceive me. What are you planning?" alvin
smiled. "I knew that you would suspect something; if you will come with me, will show you why the subway to lys is no longer important. And there is another experiment i want to try; it will not harm you, but you may not li it." "very well. I am still supposed to be your tutor, but it seems that t roles are now reversed. Where are you taking me?" "we are going to the towe of loranne, and i am go•ing to show you the world outside diaspar." jeserac

paled, but he stood his ground. Then, as if not trusting himself with words, he gave a stiff little nod and followed alvin out onto the smoothly gliding surface of the moving way. Jeserac showed no fear as they walked along the tunnel through which that cold wind blew forever into diaspar. The tunnel had changed now; the stone grille that had blocked access to the outer world was gone. It served no structural purpose, and the central computer had removed i without comment at alvin's request. Later, it might instruct the moni•tors to remember the grille again and bring it back into ex•istence. But for the moment the tunnel gaped unfenced and unguarded in the sheer outer wall of th city. Not until jeserac had almost reached the end of the air shaft did he realize that the outer world was now upon him. He looked at the widening circle of sky, and his steps became more and more uncertain until they final slowed to a halt. Alvin remembered how alystra had turned and fled from this same spot, and he wondered if he could induce jeserac to go any further. "I only asking you to look," he begged, "not to leave the city. Surely you can manage to do that!" in airlee, during his brief stay, alvin has seen a moth teaching her child to walk. He was irresistibly reminded of this as he coaxe jeserac along the corridor, making encour•aging remarks as his tutor advanced foot by reluctant foot. Jeserac, unlike khedron, was no coward. He was
prepared to fight against his compulsion, but it was a desperate struggle. Alvin was almost as exhausted as the older man by the time he had succeeded getting jeserac to a point where he could see the whole, uninterrupted sweep of the desert. Once there, the interest and strange beauty of the scene, s alien to all that jeserac had ever known in this or any previous existence, seemed to overcome his fears. He was clearly fascinated by the immense vista of the rolling sand dunes and the far-off, ancient hills. It was late afternoon, and in a little while all this land would be visited by the nigh that never came to diaspar. "I asked you to come here," said alvin, speaking quickly as if he could hardly control his impatience, "because i realize that you have earned more right than anyone to see where my travels have led me. wanted you to see the desert, and i also want you to be a witness, so tha council will know what i have done." "as i told the council, i brought this robot home from lys in the hope that the central computer would be able to break the block that has been imposed on its memories by the man known as master. By a trick which i still don't fully understand, the computer did that. Now i have access to all the memories in this machine, as well as to special skills that had been designed into it. I'm going to use one of thos skills now. Watch." on a soundless order which jeserac could only guess, the robot floated out of the tunnel entrance, picked up speed and within seconds was no more than a distant metallic gleam in the sunlight. It was flying lo over the desert, across the sand dunes that lay crisscrossed like frozen
waves. Jeserac had the unmistakable impression that it was searching-though for what, he could not imagine. Then, abruptly, the glittering speck soared away from the desert and came to rest a thousand feet above the ground. At same moment, alvin gave an explosive sigh of satis•faction and relief. He glanced quickly at jeserac, as if to say: "this is it!" at first, not knowi what to expect, jeserac could see no change. Then, scarcely believing his
eyes, he saw that a cloud of dust was slowly rising from the desert. Nothin is more terrible than movement where no move•ment should ever be again, but jeserac was beyond surprise or fear as the sand dunes began to slide apart. Beneath the desert something was stirring like a giant awakening from its sleep, and presently there came to jeserac's ears the rumble of falling earth and the shriek of rock split asunder by irresis•tible force. Then, suddenly, great geyser of sand erupted hundreds of feet into the air and the ground w hidden from sight. Slowly the dust began to settle back into a jagged wound torn across the face of the desert. But jeserac and alvin still kept their eyes fixed steadfastly upon the open sky, which a little while ago had held only the waiting robot. Now at last jeserac knew why alvin had seemed so indifferent to the decision of the council, why he had shown no emotion when he was told that the subway to lys had been closed. The covering of earth

rock could blur but could not conceal the proud lines of the ship still ascending from the riven desert. As jeserac watched, it slowly turned toward them until it had foreshortened to a circle. Then, very leisure•ly, the circl started to expand. Alvin began to speak, rather quickly, as if the time were short. "This robot was designed to be the master's companion and servant-and, above all, the pilot of his ship before he cams to lys, he landed at the
of diaspar, which now lies out there beneath those sands. Even in his day, must have been largely deserted; i think that the master's ship was one of last ever to reach earth. He lived for a while in diaspar before he went t shalmirane; the way must still have been open in those days. But he never needed the ship again, and all these ages it has been waiting out there beneath the sands. Like diaspar itself, like this robot-like everything that
the builders of the past considered really important-it was preserved by its own eternity circuits. As long as it had a source of power, it could never wear out or be destroyed; the image carried in its memory cells would never fade, and that image controlled its physical structure." the ship was now ver close, as the controlling robot guided it toward the tower. Jeserac could see that it was about a hundred feet long and sharply pointed at both ends. The appeared to be no windows or other openings, though the thick layer of earth made it impossible to be certain of this. Suddenly they were spattered with dirt as a section of the hull opened outward, and jeserac caught a glimpse
a small, bare room with a second door at its far end. The ship was anging a foot way from the mouth of the air vent, which it had approached very cautiously like a sensitive, liv•ing thing. "Good-bye, jeserac," said alvin.
"I cannot go back into diaspar to say farewell to my friends: please do tha for me. Tell eriston and etania that i hope to return soon; if i do not, grateful for all that they did. And i am grateful to you, even though you not approve of the way i have applied your lessons. "And as for the
council-tell it that a road that has once been opened cannot be closed again merely by passing a reso•lution." The ship was now only a dark stain again the sky, and of a sudden jeserac lost it altogether. He never saw its going but presently there echoed down from the heavens the most awe-inspiring of al the sounds that man has ever madethe long-drawn thunder of air falling, mile after mile, into a tunnel of vacuum drilled suddenly across the sky. Even wh the last echoes had died away into the desert, jeserac never moved. He was thinking of the boy who had gone-for to jeserac, alvin would always be a child, the only one to come into diaspar since the cycle of birth and death had been broken, so long ago. Alvin would never grow up; to him the whole universe was a plaything, a puzzle to be unraveled for his own amusement. In his play he had now found the ultimate, deadly toy which might wreck what w left of human civilization-but whatever the outcome, to him it would still be a game. The sun was now low on the horizon, and a chill wind was blowing the desert. But jeserac still waited, conquering his fears; and presently for the first tune in his life he saw the stars. Eighteen Even in diaspar, had seldom seen such luxury as that which lay before him when the inner doo of the air lock slid aside. Whatever else he had been, at least the master no ascetic. Not until some time later did it occur to alvin that all this comfort might be no vain extravagance; this little world must have been the master's only home on many long jour•neys among the stars. There were no visible controls of any kind, but the large oval screen which completely covered the far wall showed that his was no ordinary room. Ranged in a half circle before it were three low couches; the rest of the cabin was occupied two small tables and a number of padded chairs-some of them obviously not designed for human occupants. When he had made himself comfortable in front o the screen, alvin looked around for the robot. To his surprise, it had disappeared; then he located it neatly stowed away in a recess beneath the curved ceiling. It had brought the master across space to earth and then, as his servant, followed him into lys. Now it was ready, as if the intervening aeons had never been, to carry out its old duties once again. Alvin threw i an experimental command, and the great screen shivered into life. Before him

was the tower of lo•ranne, curiously foreshortened and apparently lying on its side. Further trials gave him views of the sky, of the city, and of great expanses of desert. The definition was brilliantly, almost unnaturally, clear, although there seemed to be no actual magnification. Alvin experimented for a little while until he could obtain any view he wished; then he was ready to start. "Take me to lys." the command was a simple one, but how could the s obey it when he himself had no idea of the direction? Alvin had not conside this, and when it did occur to him the machine was already moving across th desert at a tremendous speed. He shrugged his shoulders, ac•cepting thankfully the fact that he now had servants wiser than himself. It was difficult to judge the scale of the picture racing up the screen, but many miles must be passing every minute. Not far from the city the color of the ground had changed abrupt•ly to a dull gray, and alvin knew that he was passing over t bed of one of the lost oceans. Once diaspar must have been very near the s though there had never been any hint of this even in the most ancient recor Old though the city was, the oceans must have passed away long before its founding. Hundreds of miles later, the ground rose sharply and the desert returned. Once alvin halted his ship above a curious pattern of intersecting lines, showing faintly through the blanket of sand. For a moment it puzzled him; then he re•alized that he was looking down upon the ruins of some for•gotten city. He did not stay for long; it was heartbreaking to think tha billions of men had left no other trace of their ex•istence save these furro in the sand. The smooth curve of the horizon was breaking up at last, crinkling into mountains that were beneath him almost as soon as they were glimpsed. The machine was slowing now, slowing and falling to earth in a gre arc a hundred miles in length. And then below him was lys, its forests and endless rivers forming a scene of such incomparable beauty that for a while could go no further. To the east, the land was shad•owed and the great lake floated upon it like pools of darker night. But toward the sunset, the water danced and sparkled with light, throwing back toward him such colors as he h never imagined. It was not difficult to locate airlee-which was fortunate, for the robot could guide him no further. Alvin had expected this, and felt a little glad to have discovered some limits to its powers. It was unlikely th it would ever have heard of airlee, so the position of the village would ne have been stored in its memory cells. After a little experimenting, alvin brought his ship to rest on the hillside that had given him his first glimp of lys. It was quite easy to control the machine; he had only to in•dicate general desires and the robot attended to the details. It would, he imagined, ignore dangerous or impossible orders, though he had no intention of giving
any if he could avoid it. Alvin was fairly certain that no one could have his arrival. He thought this rather important, for he had no desire to engag in mental combat with seranis again. His plans were still somewhat vague, but he was running no risks until he had established friendly relations. The robo could act as his ambassador, while he remained safely in the ship. He met n one on the road to airlee. It was strange to sit in the spaceship while hi field of vision moved effortlessly along the familiar path, and the whispering of the forest sounded in his ears. As yet he was unable to identify himself fully with the robot, and the strain of controlling it was still considerable It was nearly dark when he reached airlee, and the little houses were floati in pools of light. Alvin kept to the shadows and had almost reached seranis' home before he was discovered. Suddenly there was an angry, high-pitched buzz•ing and his view was blocked by a flurry of wings. He recoiled involuntarily before the onslaught; then he realized what had happened. Krif
was once again expressing his resentment of anything that flew without wings. Not wishing to hurt the beautiful but stupid creature, alvin brought the robo to a halt and endured as best he could the blows that seemed to be raining upon him. Though he was sitting in comfort a mile away, he could not avoid flinching and was glad when hilvar came out to investigate at his master's approach krif departed, still buzzing bale•fully. In the silence that
followed, hilvar stood looking at the robot for a while. Then he smiled.

"Hello, alvin," he said. "I'm glad you've come back. Or are you still in diaspar?" not for the first time, alvin felt an envious admiration for the speed and precision of hilvar's mind. "No," he said, wondering as he did so how clearly the robot echoed his voice. "I'm in airlee, not very far away. i'm staying here for the present." hilvar laughed. I think that's just as well. Seranis has forgiven you, but as for the assembly-well, that is another matter. There is a conference going on here at the moment-the first we have ever had in airlee.,, "do you mean," asked alvin, "that your councilors have actually come here? With your telepathic powers, i should have thought that meetings weren't necessary." "they are rare, but there are times when they ar felt desirable. I don't know the exact nature of the crisis, but three senators are already here and the rest are expected soon." alvin could not help smiling at the way in which events in diaspar had been mirrored here. Wherever he went, he now seemed to be leaving a trail of consternation and alarm be,•hind him. I think it would be a good idea," he said, "if i could talk to this assembly of yours-as long as i can do so in safety." "it woul safe for you to come here yourself," said hilvar, "if the assembly promises not to try and take over your mind again. Otherwise, i should stay where yo are. I'll lead your robot to the senators-they'll be rather upset to see it. alvin felt that keen but treacherous sense of enjoyment and exhilaration as h followed hilvar into the house. He was meeting the rulers of lys on more eq terms now; though he felt no rancor against them, it was very pleasant to k that he was now master of the situation, and in command of powers which eve yet he had not fully turned to account. The door of the conference room was locked, and it was some time before hilvar could attract attention. The minds of the senators, it seemed, were so completely engaged that it was difficult to break into their deliberations. Then the walls slid reluctantly aside, and alvin moved his robot swiftly forward into the chamber. The three senators froze in their seats as he floated toward them, but only the slightest flick of surprise crossed se•ranis's face. Perhaps hilvar had already sent her a warning, or perhaps she had expected that, sooner or later, alvin would
return. "Good evening," he said politely, as if this vicarious entry were the most natural thing in the world. "I've decided to come back." their surprise certainly exceeded his expectations. One of the senators, a young man with graying hair, was the first to recover. "How did you get here?" he gasped. reason for his astonishment was obvious. Just as di•aspar had done, so lys must also have put the subway out of action. "Why, i came here just as i last time," said alvin, unable to resist amusing himself at their expense. Tw of the senators looked fixedly at the third, who spread his hands in a gest of baffled resignation. Then the young man who had addressed him before spoke again. "Didn't you have any-difficulty?" he asked. "None at all," said alvin, determined to increase their confusion. He saw that he had succeeded. "I've come back," he continued, "under my own free will, and because i have some important news for you. However, in view of our previous disagreement i'm remaining out of sight for the moment. If i appear personally, will you promise not to try to restrict my movements again?" no one said anything for while, and alvin wondered what thoughts were being silently interchanged. Then se•ranis spoke for them all. "We won't attempt to control you again-though i don't think we were very successful before." "very well," replied alvin. "1
Will come to airlee as quick•ly as i can." he waited until the robot had returned; then, very care•fully, he gave the machine its instructions and made it repeat them back to him. Seranis, he was quite sure, would not break her word; nevertheless he preferred to safeguard his line of retreat. The air loc closed silently behind him as he left the ship. A moment later there was a whispering "hiss..." Like a long-drawn gasp of surprise, as the air made way for the ris•ing ship. For an instant a dark shadow blotted out the stars; t the ship was gone. Not until it had vanished did alvin realize that he had made a slight but annoying miscalculation of the kind that could bring the best-laid plans to disaster. He had forgotten that the robot's senses were
more acute than his own, and the night was far darker than he had expected.

More than once he lost the path completely, and several times he barely avoided colliding with trees. It was almost pitch-black in the forest, and once something quite large came toward him through the undergrowth. There was
the faintest crackling of twigs, and two emerald eyes were looking steadfastly at him from the level of his waist. He called softly, and an in•credibly lo tongue rasped across his hand. A moment later a powerful body rubbed affectionately against him and de•parted without a sound. He had no idea what it could be. Presently the lights of the village were shining through the trees ahead, but he no longer needed their guidance for the path beneath his feet had now become a river of dim blue fire. The moss upon which he was walking was luminous, and his footprints left dark patches which slowly disappeared behind him. It was a beautiful and entrancing sight, and when
alvin stooped to pluck some of the strange moss it glowed for minutes in hi cupped hands before its radiance died. Hilvar met him for the second time outside the house, and for the second time introduced him to seranis and the senators. They greeted him with a kind of wary and reluctant respect; if the wondered where the robot had gone, they made no comment. "I'm very sorry," alvin began, "that i had to leave your country in such an undignified fashio It may interest you to know that it was nearly as difficult to escape from diaspar." he let that remark sink in, then added quickly, "i have told my people all about lys, and i did my best to give a favorable impression. But diaspar will have nothing to do with you. In spite of all i could say, it wishes to avoid contamination with an inferior culture." it was most
satisfying to watch the senators' reactions, and even the urbane seranis colored slightly at his words. If he could make lys and diaspar sufficiently annoyed with each other, thought alvin, his problem would be more than half solved. Each would be so anxious to prove the superiority if its own way of life that the barriers between them would soon go down. "Why have you come back to lys?" asked seranis. "Because i want to convince you, as well as diaspar, that you have made a mistake." he did not add his other reason -th in lys was the only friend of whom he could be certain and whose help he needed. The senators were still silent, waiting for him to con•tinue, and he knew that looking through their eyes and listening through their ears were
many other unseen intel•figences. He was the representative of diaspar, and the whole of lys was judging him by what he might say. It was a great responsibility, and he felt humbled before it. He marshaled his thoughts and then began to speak. His theme was diaspar. He painted the city as he had seen it, dreaming on the breast of the desert, its towers glow•ing like captive rainbows against the sky. From the treasure house of memory he recalled the songs that the poets of old had written in praise of diaspar, he spoke of the count•less men who had spent their lives to increase its
beauty. No one, he told them, could ever exhaust the city's treasures, howeve long they lived; always there would be something new. For a while he describ some of the wonders which the men of diaspar had wrought; he tried to make them catch a glimpse at least of the loveliness that the artists of the pas had created for men's eternal admiration. And he wondered a little wistfully
if it were indeed true that the music of diaspar was the last sound that e had ever broadcast to the stars. They heard him to the end without interruption or ques•tioning. When he had finished it was very late, and alvi felt more tired than he could ever before remember. The strain and excitement of the long day had told on him at last, and quite suddenly he was asleep. When he awoke, he was in an unfamiliar room and it was some moments before remembered that he was no longer in diaspar. As consciousness returned, so th light grew around him, until presently he was bathed in the soft, cool radiance of the morning sun, streaming through the now transparent walls. He lay in drowsy half-awareness, recalling the events of the previous day and wondering what forces he had now set in motion. With a soft, musical sound, one of the walls began to pleat itself up in a manner so complicated that eluded the eye. Hilvar stepped through the opening that had been formed and looked at alvin with an expression half of amusement, half of serious concern

"Now that you're awake, alvin," he said "perhaps you'll at least tell me wha your next move is, and how you man• aged to return here. The senators are leaving to look at the subway; they can't understand how you managed to come back through it. Did you?" alvin jumped out of bed and stretched himself mightily. "Perhaps we'd better overtake them," he said. "I don't want to make them waste their time. As for the question you asked me-in a little while i show you the answer to that." they had almost reached the lake before they overtook the three senators, and both parties exchanged slightly
self•conscious greetings. The committee of investigation could see that alvin knew where it was going, and the unexpected encounter had clearly put it somewhat at a loss. "I'm afraid i misled you last night," said alvin cheerfully. "I didn't come to lys by the old route, so your attempt to clos it was quite unnecessary. As a matter of fact, the council of diaspar also closed it at their end, with equal lack of success." the senators' faces wer a study in perplexity as one solu•tion after another chased through their brains. "Then how did you get here?" said the leader. There was a sudden, dawning comprehension in his eyes, and alvin could tell that he had begun to guess the truth. He wondered if he had intercepted the command his mind had just sent winging across the mountains. But he said nothing, and merely
pointed in silence to the northern sky. Too swiftly for the eye to follow, needle of silver light arched across the mountains, leaving a mile-long trail of in•candescence. Twenty thousand feet above lys, it stopped. There was no deceleration, no slow braking of its colos•sal speed. It came to a halt instantly, so that the eye that had been following it moved on across a quarter of the heav•ens before the brain could arrest its motion. Down from the skies crashed a mighty petal of thunder, the sound of air battered and smashed by the violence of the ship's passage. A little later the ship itsel gleaming splendidly in the sun•light came to rest upon the hillside a hundred yards away. It was difficult to say who was the most surprised, but alvin w the first to recover. As they walked-very nearly running-toward the spaceship, he wondered if it normally traveled in this meteoric fashion. The thought was disconcert•ing, although there had been no sensation of movement on his
voyage. Considerably more puzzling, however, was the fact that a day ago this resplendent creature had been hidden be•neath a thick layer of iron-hard
rock-the coating it had still retained when it had torn itself loose from th desert. Not until alvin had reached the ship, and burned his fingers by incautiously resting them on the hull, did he understand what had happened. Near the stern there were still traces of earth, but it had been fused into lava. All the rest had been swept away, leaving uncovered the stubborn shell which neither time nor any natural force could ever touch. With hilvar by hi side, alvin stood in the open door and looked back at the silent senators. wondered what they were thinking-what, indeed, the whole of lys was thinking. From their expressions, it almost seemed as if they were be•yond thought. I going to shalmirane' " said alvin, "and i will be back in airlee within an hour or so. But that is only a begin•ning, and while i am away, there is thought i would leave with you. "This is no ordinary flyer of the kind in which men traveled over the earth. It is a spaceship, one of the fastest ev built. If you want to know where i found it, you will find the an•swer in diaspar. But you will have to go there, for diaspar will never come to you. he turned to hilvar, and gestured to the door. Hilvar hesi•tated for a momen only, looking back once at the familiar scenes around him. Then he stepped forward into the air lock. The senators watched until the ship, now moving quite slowly-for it had only a little way to go-had disappeared into the south. Then the gray-haired young man who led the group shrugged his shoulder philosophically and turned to one of his colleagues. "You've always opposed us for wanting change," he said, "and so far you have won. But i don't think future lies with either of our groups now. Lys and diaspar have both come t the end of an era, and we must make the best of it." "i am afraid you ar right," came the gloomy reply. "This is a crisis, and alvin knew what he wa saying when he told us to go to diaspar. They know about us now, so there

no further purpose in concealment. I think we had better get in touch with cousins-we may find them more anxious to cooperate now." "but the subway is closed at both endsl" "We can open ours; it will not be long before diasp does the same." the minds of the senators, those in airlee and those scatter over the whole width of lys, considered the pro•posal and disliked it
heartily. But they saw no alternative. Sooner than he had any right to expect, the seed that alvin had planted was beginning to flower. The mountains were still swimming in shadow when they reached shalmirane. From their height the great bowl of the fortress looked very small; it seemed
impossible that the fate of earth had once depended on that tiny ebon circle When alvin brought the ship to rest among the ruins by the lakeside, the desolation crowded in upon him, chilling his soul. He opened the air lock, a the stillness of the place crept into the ship. Hilvar, who had scarcely spoken during the entire flight, asked quietly: "why have you come here
again?" alvin did not answer until they had almost reached the edge of the lake. Then he said: "i wanted to show you what this ship was like. And i hoped that the polyp might be in existence once more; i feel i owe it a d and i want to tell it what i've discovered." "in that case," replied hilvar, "you will have to wait. You have come back much too soon." alvin had expect that; it had been a remote chance and he was not disappointed that it had failed. The waters of the lake were perfectly still, no longer beating with that steady rhythm that had so puzzled them on their first visit. He knelt down at the water's edge and peered into the cold, dark depths. Tiny translucent bells, trailing almost invisible tentacles, were drifting to and
fro beneath the surface. Alvin plunged in his hand and scooped one up. He dropped it at once, with a slight exclamation of annoyance. It had stung him Some day-perhaps years, perhaps centuries in the future -these mindless
jellies would reassemble and the great polyp would be reborn as its memories linked together and its con•sciousness flashed into existence once again.
Alvin wondered how it would receive the discoveries he had made; it might no be pleased to learn the truth about the master. Indeed, it might refuse to admit that all its ages of patient waiting had been in vain. Yet had they? Deluded though these creatures might have been, their long vigil had at last brought its reward. As if by a miracle, they had saved from the past knowle that else might have been lost forever. Now they could rest at last, and th creed could go the way of a million other faiths that had once thought themselves eternal. Nineteen Hilvar and alvin walked in reflective silence back to the waiting ship, and presently the fortress was once more a dark shadow among the hills. It dwindled swiftly until it became a black and lidless eye, staring up forever into space, and soon they lost it in the gr panorama of lys. Alvin did nothing to check the machine; still they rose unt the whole of lys lay spread beneath them, a green island in an ocher sea. Never before had alvin been so high; when finally they came to rest the who crescent of the earth was visible below. Lys was very small now, only an emerald stain against the rusty desert-but far around the curve of the globe something was glittering like a man-colored jewel. And so for the first time, hilvar saw the city of diaspar. They sat for a long while watching the eart turn be•neath them. Of all man's ancient powers, this surely was the one he could least afford to lose. Alvin wished he could show the world as he saw now to the rulers of lys and di•aspar. "Hilvar," he said at last, "do you think that what i'm doing is right?" the question surprised hilvar, who did not suspect the sudden doubts that sometimes overwhelmed his friend, and still knew nothing of alvin's meeting with the central com•puter and the impact
which that had had upon his mind. It was not an easy question to answer dispassionately; like khedron, though with less cause, hilvar felt that his
own character was becoming submerged. He was being sucked helplessly into the vortex which alvin left behind him on his way through life. "I believe you right," hilvar answered slowly. "Our two peoples have been separated for long enough." that, he thought, was true, though he knew that his own feel•ings must bias his reply. But alvin was still worried. "There's one problem that

bothers me," he said in a troubled voice, "and that's the difference in our life spans." he said no more, but each knew what the other was think•ing. I been worried about that as well," hilvar admitted, "but i think the problem will solve itself in time when our people get to know each other again. We can't both be right -our lives may be too short, and yours are certainly fa too long. Eventually there will be a compromise." alvin wondered. That way, i was true, lay the only hope, but the ages of transition would be hard indee He remem•bered again those bitter words of seranis: "both he and 1 will have been dead for centuries while you are still a young man." very well he woul accept the conditions. Even in diaspar all friendships lay under the same shadow; whether it was a hundred or a million years away made little differ•ence at the end. Alvin knew, with a certainty that passed all logic, that the welfare of the race demanded the mingling of these two cul•tures; i such a cause individual happiness was unimportant. For a moment alvin saw humanity as something more than the living background of his own life, and h accepted with•out flinching the unhappiness his choice must one day bring. Beneath them the world continued on its endless turning. Sensing his friend's mood. Hilvar said nothing, until present in alvin broke the silence. "When i first left diaspar," he said, "i did not know what i hoped to find. Lys wo have satisfied me once-more than satisfied me-yet now everything on earth
seems so small and unimportant. Each discovery i've made has raised bigger questions, and opened up wider horizons. I wonder where it will end...." Hilvar had never seen alvin in so thoughtful a mood, and did not wish to
interrupt his soliloquy. He had learned a great deal about his friend in the last few minutes. "The robot told me," alvin continued, "that this ship can reach the seven suns in less than a day. Do you think i should go?" "do y think i could stop you?" hilvar replied quietly. Alvin smiled. "That's no answer," he said. "Who knows what lies out there in space? The invaders may have left the universe, but there may be other intelligences unfriendly to man." "why should there be?" hilvar asked. "That's one of the questions our philosophers have been debating for ages. A truly intelligent race is not likely to be unfriendly." "but the invaders-?" "they are an enigma, i admit.
1F they were really vicious, they must have destroyed themselves by now. And even if they have not-" hilvar pointed to the unending deserts below. "Once had an empire. What have we now that they would covet?" alvin was a little surprised that anyone else shared this point of view, so closely allied to h own. "Do all your people think this way?" he asked. "Only a minority. The average person doesn't worry about it, but would probably say that if the invaders really wanted to destroy earth, they'd have done it ages ago. I don suppose anyone is actually afraid of them." "things are very different in diaspar," said alvin. "My people are great cowards. They are terrified of leaving their city, and i don't know what will happen when they hear that i located a spaceship. Jeserac will have told the council by now, and i would like to know what it is doing." "i can tell you that. It is preparing to receive its first dele•gation from lys. Seranis has just told me." alvin
looked again at the screen. He could span the dis•tance between lys and diaspar in a single glance; though one of his aims had been achieved, that seemed a small mat•ter now. Yet he was very glad; now, surely, the long age of sterile isolation would be ending. The knowledge that he had succeeeded in what had once been his main mission cleared away the last doubts from al•vin mind. He had fulfilled his purpose here on earth, more swiftly and more thoroughly than he had dared to hope. The way lay clear ahead for what migh be his last, and would cer•tainly be his greatest, adventure. "Will you com with me, hilvar?" he said, all too con•scious of what he was asking. Hilvar looked at him steadfastly. "There was no need to ask that, alvin," he said. told seranis and all my friends that i was leaving with you •a good hour ago." They were very high when alvin gave the robot its final instructions. The ship had come almost to rest and the earth was perhaps a thousand miles below, nearly filling the sky. It looked very uninviting; alvin wondered how many ships in the past had hovered here for a little while and then con•tin

on their way. There was an appreciable pause, as if the robot was check•ing controls and circuits that had not been used for geological ages. Then came very faint sound, the first that alvin had ever heard from a machine. It wa tiny humming, which soared swiftly octave by octave until it was lost at the edge of hearing. There was no sense of change of motion, but suddenly he noticed that the stars were drifting across the screen. The earth reappeared, and rolled past-then appeared again, in a slightly different position. The
ship was "hunting," swinging in space like a compass needle seeking the north For minutes the skies turned and twisted around them, until at last the ship came to rest, a giant projectile aimed at the stars. Centered in the screen the great ring of the seven suns lay in its rainbow-hued beauty. A little o earth was still visi•ble as a dark crescent edged with the gold and crimson the sunset. Something was happening now, alvin knew, be•yond all his
experience. He waited, gripping his seat, while the seconds drifted by and th seven suns glittered on the screen. There was no sound, only a sudden wrench that seemed to blur the vision-but earth had vanished as if a giant hand ha whipped it away. They were alone in space, alone with the stars and a strangely shrunken sun. Earth was gone as though it had never been. Again ca that wrench, and with it now the faintest murmur of sound, as if for the f time the generators were exerting some appreciable fraction of their power.
Yet for a moment it seemed that nothing had happened; then alvin realized th the sun itself was gone and that the stars were creeping slowly past the sh He looked back for an instant and saw-nothing. All the heavens behind had vanished utterly, obliterated by a hemisphere of night. Even as he watched, he could see the stars plunge into it, to disappear like sparks falling upon water. The ship was traveling far faster than light, and alvin knew that the familiar space of earth and sun held him no more. When that sudden, vertiginous wrench came for the third time, his heart almost stopped beating. The strange blurring of vision was unmistakable now: for a moment hi surround•ings seemed distorted out of recognition. The meaning of that
distortion came to him in a flash of insight he could not ex•plain. It was real and no delusion of his eyes. Somehow he was catching, as he through the thin film of the present, a glimpse of the changes that were occurring in the space around him. At the same instant the murmur of the generators rose to a roar that shook the ship-a sound doubly impressive for was the first cry of protest that alvin had ever heard from a machine. Then was all over, and the sudden silence seemed to ring in his ears. The great generators had done their work; they would not be needed again until the end of the voyage. The stars ahead flared blue-white and vanished into the ultraviolet. Yet by some magic of science or nature the seven suns were stil visible, though now their positions and colors were subtly changed. The ship was hurtling toward them along a tunnel of darkness, beyond the boundaries of space and time, at a velocity too enormous for the mind to contemplate. It hard to believe that they had now been flung out of the solar system at a speed which unless it were checked would soon take them through the heart of the galaxy and into the greater emptiness beyond. Neither alvin nor hilvar could conceive the real immensity of their journey; the great sagas of exploration had completely changed man's outlook toward the universe and even now, millions of centuries later, the ancient traditions had not wholly died. There had once been a ship, legend whispered, that had circumnavigated the cosmos between the rising and the setting of the sun. The billions of miles between the stars meant nothing before such speeds. To alvin this voyage was very little greater, and per•haps less dangerous, than his first journey to lys. It was hilvar who voiced both their thoughts as the seven suns slowly brightened ahead. "Alvin," he remarked, "that formation can't possibly be natural." the other nodded. "I've thought that for years, but it still seems fantastic." "the system may not have been built by man," agreed hil•var, "but intelligence must have created it. Nature could never have formed that perfect circle of stars, all equally brilliant. And there's nothing else in the
visible universe like the cen•tral sun." "why should such a thing have been

made, then?" "oh, i can think of many reasons. Perhaps it's a signal, so th any strange ship entering our universe will know where to look for life. Perhaps it marks the center of galactic administration. Or perhaps-and somehow
i feel that this is the real explanation-it's simply the greatest of all wor of art. But it's foolish to speculate now. In a few hours we shall know th truth." "we shall know the truth." perhaps, thought alvin-but how much of it shall we ever know? It seemed strange that now, while he was leaving diaspar and indeed earth itself, at a speed beyond all comprehension, his mind should turn once more to the mystery of his origin. Yet perhaps it was not so surprising; he had learned many things since he had first arrived in lys, bu until now he had not had a single mo•ment for quiet reflection. There was nothing he could do now but sit and wait; his immediate future was controlle by the wonderful machine -surely one of the supreme engineering achievements
of all time-that was now carrying him into the heart of the uni•verse. Now the moment for thought and reflection, whether he wished it or not. But firs he would tell hilvar all that had happened to him since their hasty parting only two days before. Hilvar absorbed the tale without comment and without asking for any explanations; he seemed to understand at once everything that alvin described, and showed no signs of surprise even when he heard of the meeting with the cen•tral computer and the operation it had performed upon th robot's mind. It was not that he was incapable of wonder, but that the hist of the past was full of marvels that could match anything in alvin's story. "It's obvious," he said, when alvin had finished talking, "that the central computer must have received special in•structions regarding you when it was built. By now, you must have guessed why." "I think so. Khedron gave me p of the answer when he explained how the men who designed diaspar had taken steps to prevent it becoming decadent." "do you think you-and the other
uniques before you •are part of the social mechanism which prevents complete stagnation? So that whereas the jesters are short-term cor•recting factors,
you and your kind are long-term ones?" hilvar had expressed the idea better than alvin could, yet this was not exactly what he had in mind. "I believe truth is more complicated than that. It al•most looks as if there was a conflict of opinion when the city was built, between those who wanted to shu it off completely from the outside world, and those who wanted to maintain some contacts. The first faction won, but the others did not admit defeat. I think yarlan zey must have been one of their leaders, but he was not powerf enough to act openly. He did his best, by leaving the subway in existence a by in•suring that at long intervals someone would come out of the hall of creation who did not share the fears of all his fellow men, in fact, i wonder-" alvin paused, and his eyes veiled with thought so that for a moment he seemed oblivious of his surroundings. "What are you thinking now?" asked hilvar., "it's just occurred to me-perhaps 1 am yarlan zey. It's perfectly possible. He may have fed his personality into memory banks, relying on it t break the mold of diaspar before it was too firmly established. One day i m discover what happened to those earlier uniques; that may help fill in the gaps in the picture." "and yarlan zey-or whoever it was-also instructed the central computer to give special assistance to the uniques, whenever they were created," mused hilvar, following this line of logic. "That's right. The
ironic thing is that i could have got all the information i needed direct f the central computer, without any assistance from poor khedron. It would have told me more than it ever told him. But there's no doubt that he saved me good deal of time, and taught me much that i could never have learned by myself." "i think your theory covers all the known facts," said hilvar cautiously. "Unfortunately, it still leaves wide open the biggest problem of
all-the original purpose of diaspar. Why did your people try to pretend that the outer world didn't exist? That's a question i'd like to see answered." "it's a question i intend to answer," replied alvin. "But i don't know when- how." so they argued and dreamed, while hour by hour the seven suns drifted apart until they had filled that strange tunnel of night in which the ship riding. Then, one by one, the six outer stars vanished at the brink of

darkness and at last only the central sun was left. Though it could no long be fully in their space, it still shone with the pearly light that marked i out from all other stars. Minute by minute its bril•liance increased, until presently it was no longer a point but a tiny disc. And now the disc was beginning to expand be•fore them. There was the briefest of warnings: for a moment a deep, bell-like note vibrated through the room. Alvin clenched the arms of his chair, though it was a futile enough gesture. Once again the gr generators exploded into life, and with an abruptness that was almost
blinding, the stars re•appeared. The ship had dropped back into space, back into; the universe of suns and planets, the natural world where; nothing coul move more swiftly than light. They were already within the system of the sev suns, for the great ring of colored globes now dominated the sky. And what sky it was! All the stars they had known, all the: familiar constellations, had gone. The milky way was no longer a faint band of mist far to one sid the heavens; they were now at the center of creation, and its great circle divided the universe in twain. The ship was still moving very swiftly towar the cen•tral sun, and the six remaining stars of the system were colored beacons ranged around the sky. Not far from the nearest of them were the ti sparks of circling planets, worlds that must have been of enormous size to b visible over such a distance. The cause of the central sun's nacreous light was now clearly visible. The great star was shrouded in an envelope of gas which softened its radiation and gave it its characteristic color. The surrounding nebula could only be seen indirectly, and it was twisted into strange shapes that eluded the eye. But it was there, and the longer one stared the more extensive it seemed to be. "Well, alvin," said hilvar, "we have a good many worlds to take our choice from. Or do you hope to explore them all?" "it's lucky that won't be necessary," admitted alvin. "If we can make contact anywhere, we'll get the information we need. The logical thing would be to head for the largest planet of the central sun." "unless it's t large. Some planets, i've heard, were so big that human life could not exist on them-men would be crushed under their own weight." "i doubt if that will true here, since i'm sure this sys•tem is entirely artificial. In any case, we'll be able to see from space whether there are any cities and buildings." hilvar pointed to the robot. "Our problem has been solved for us. Don't
forget-our guide has been here before. He is taking us home and i wonder wh he thinks about it?" that was something that alvin had also wondered. But wa it accurate-did it make any sense at all-to imagine that the robot felt anything resembling human emotions now that it was returning to the ancient home of the master, after so many aeons? In all his dealings with it, since the central computer had released the blocks that made it mute, the robot ha
-never shown any sign of feelings or emotion. It had answered his questions and obeyed his commands, but its real personality had proved utterly inaccessible to him. That it had a person•ality alvin was sure; otherwise he would not have felt that obscure sense of guilt which afflicted him when he recalled the trick he had played upon it-and upon its now dormant companion. It still believed in everything that the master had taught it; though it had seen him fake his miracles and tell lies to his followers, these inconvenient facts did not affect its loyalty. It was able, as had many humans before it to •reconcile two conflicting sets of data. Now it was following its immemorial memories back to heir origin. Almost lost in the glare of the central sun was a vale spark of light, with around it the fainter gleams of yet smaller worlds. Their enormous journey was coming to it end; in a little while they would know if it had been in vain Twenty The planet they wer approaching was now only a few million miles away, a beautiful sphere of multicolored light. There could be no darkness anywhere upon its surface, for as it turned beneath the central sun, the other stars would march one by on across its skies. Alvin now saw very clearly the meaning of the master's dyi words: "it is lovely to watch the colored shadows on the planets of eternal light." now they were so close that they could see continents an oceans and faint haze of atmosphere. Yet there was som thing puzzling about its markings

and presently they realiz that the divisions between land and water were curious regular. This planet's continents were not as nature had le them-but how small a task the shaping of a world mu have been to those who built i suns! "Those aren't oceans at all!" hilvar exclaimed suddenly "look-you can
see markings in them!" not until the planet was nearer could alvin see clear what his friend meant. Then he noticed faint bands and lines along the continental borders well inside what he had take to be the limits of the se The sight filled him with a sudden doubt, for he knew too well the meaning those lines. Had seen them once before in the desert beyond diaspar, they to him that his journey had been in vain. "This planet is as dry as earth," h said dully. "Its water has all gone-those markings are the salt beds where seas have evaporated." "they would never have let that happen," replied hilvar "i think that, after all, we are too late." his disappointment was so bitter that alvin did not trust himself to speak again but stared silently at the great world ahead. With impressive slowness the planet turned benea the ship, and its surface rose majestically to meet them. No they could see
buildings-minute white incrustations eve where save on the ocean beds themselves. Once this world had been the center of the universe. Now it was still, the air was empty and on the ground were no of the scurrying dots t spoke of life. Yet the ship was still sliding purposefully over the frozen s of stone-a sea which here and there had gathered itself into great waves tha challenged the sky. Presently the ship came to rest, as if the robot had at last traced its memories to their source. Below them was a col•umn of
snow-white stone springing from the center of an immense marble amphitheater. Alvin waited for a little while; then, as the machine remained motionless, he directed it to land at the foot of the pillar. Even until now, alvin had h hoped to find life on this planet. That hope vanished instantly as the air lock opened. Never before in his life, even in the desolation of shalmirane, had he been in utter silence. On earth there was always the murmur of voice the stir of living creatures, or the sighing of the wind. Here were none of these, nor ever would be again. "Why did you bring us to this spot?" asked alvin. He felt little interest in the answer, but the momentum of his quest still carried him on even when he had lost all heart to pursue it further. "The master left from here," replied the robot. "I thought that would be the explanation," said hilvar. "Don't you see the irony of all this? He fled fro this world in disgrace now look at the memorial they built for him!" the gr column of stone was perhaps a hundred times the height of a man, and was s in a circle of metal slightly raised above the level of the plain. It was featureless and bore no inscription. For how many thousands or millions of years, wondered alvin, had the master's disciples gathered here to do him honor? And had they ever known that he died in exile on distant earth? It
no difference now. The master and his disciples alike were buried in oblivion "Come outside," urged hilvar, trying to jolt alvin out of his mood of depression. "We have traveled halfway across the universe to see this place.
At least you can make the effort to step outdoors." despite himself, alvin smiled and followed hilvar through the air lock. Once outside, his spirits began to revive a little. Even if this world was dead, it must contain much interest, much that would help him to solve some of the mysteries of the pa The air was musty, but breathable. Despite the many suns in the sky, the temperature was low. Only the white disc of the central sun provided any rea heat, and that seemed to have lost its strength in its passage through the nebulous haze around the star. The other suns gave their quota of color, but no warmth. It took only a few minutes to make sure that the obelisk could them nothing. The stubborn material of which was made showed definite signs o age; its edges were rounded, and the metal on which it was standing had bee worn away by the feet of generations of disciples and visitors. It was stran to think that they might be the last many billions of human beings ever to stand upon this spot hilvar was about to suggest that they should return the ship and fly across to the nearest of the surrounding buildings when alvin noticed a long, narrow crack in th marble floor of the amphitheater. They

walked along it for a considerable distance, the crack widening all the time un•til presently it was too broad for a man's legs to straddle. A moment la they stood beside its origin. The surface of the arena had been crushed and splintered into an enormous shallow depression, more than a mile long. No intelligence,no imagination was needed to picture its cause. Ages ago though certainly long after this world had been deserted• immense cylindrical shape
had rested here, then lift once more into space and left the planet to its memories. Who had they been? Where had they come from? Alvin could only star and wonder. He would never know if he had missed these earlier visitors by thousand or a million years they walked in silence back to their own ship ( tiny that would have looked beside the monster which once had rested here!) and flew slowly across the arena until they came to the most impressive of buildings flanking it. As they landed in front of the ornate entrance, hilvar pointed out something that alvin had noticed at the same moment. "These buildings don't look safe. See all that fallen stone over there-it's a miracl they're still standing. If there were any storms on this planet, they would have been flattened ages ago. I don't think it would be wise to go inside anyof them." "i'm not going to; i'll send the robot-it can travel far faster than we can, and it won't make any disturbance which might bring the roof crashing down on top of it." hilvar approved of this precaution, but he also insistet on one which alvin had overlooked. Before the robot lef on its reconnaissance, alvin made it pass on a set of instructions to the almost equally intelligent brain of the ship, so that whatever happened to their
pilot they could at least return safely to earth. It took little time to convince both of them that this work had nothing to offer. Together they watched miles of empty dust-carpeted corridors and passageways drift across thd screen as the robot explored these empty labyrinths. All buildings designed by intelligent beings, whatever form their bodied may take, must
comply with certain basic laws, and after i while even the most alien forms architecture or design fail to evoke surprise, and the mind becomes hypnotized by sheet repetition, incapable of absorbing any more impressions. These buildings, it seemed, had been purely residential, and the beings who had
lived in them had been approximately humanoid size. They, might well have bee men; it was true that there were a surprising number of rooms and enclosures that could be entered only by flying creatures, but that did not mean that builders of this city were winged. They could have used the personal antigravity devices that had once been in common use but of which there was now no trace in diaspar. "Alvin," said hilvar at last, "we could spend a million years exploring these buildings. It's obvious that they've not merely been abandoned-they were carefully stripped of everything valuable that they possessed. We are wasting our time." "then what do you suggest?" asked alvin. "We should look at two or three other areas of this planet and see if they the same-as i expect they are. Then we should make an equally quick survey the other planets, and only land if they seem fundamentally different or we notice something unusual. That's all we can hope to do un•less we are going stay here for the rest of our lives." it was true enough; they were trying contact intelligence, not to carry out archaeological research. The former
task could be achieved in a few days, if it could be achieved at all. The latter would take centuries of labor by armies of men and robots. They left the planet two hours later, and were thankful enough to go. Even when it ha been bustling with life, al•vin decided, this world of endless buildings would have been very depressing. There were no signs of any parks, any open spaces where there could have been vegetation. It had been an utterly sterile world, and it was hard to imagine the psy•chology of the beings who had lived here If the next planet was identical with this, alvin decided, he would probably abandon the search there and then. It was not; indeed, a greater contrast would have been impossible to imagine. This planet was nearer the sun, and even from space it looked hot. It was partly covered with low clouds, indicating that water was plentiful, but there were no signs of any oceans. Nor was there any sign of intelligence; they circled the planet twice without

glimpsing a single artifact of any kind. The entire globe, from poles down t the equator, was clothed with a blanket of virulent green. "I think we shoul be very careful here," said hilvar. "This world is alive-and i don't like th color of that vegetation. It would be best to stay in the ship, and not to open the air lock at all." "not even to send out the robot?" "no, not even that. You have forgotten what disease is, and though my people know how to deal with it we are a long way from home and there may be dangers here wh we cannot see. I think this is a world that has run amok. Once it may hav been all one great garden or park, back when it was abandoned nature took o again. It could never have been like this while the system was inhabited." alvin did not doubt that hilvar was right. There was some thing evil, something hostile to all the order and regularity on which lys and diaspar were based, in the biological an. Archy below. Here a ceaseless battle had raged for a billion years; it would be well to be wary of the survivors. T came cautiously down over a great level plain, so uniform that its flatness posed an immediate problem. The plain was bordered by higher ground,
completely cover with trees whose height could only be guessed-they were so tightly packed, and so enmeshed with undergrowth, that their trunks were virtually buried. There were so many winged creatures flying among their upper branches, though they moved so swiftly that it was impossible to tell whether the were birds or insects-or neither. Here and there a forest giant had managed to climb a few scores of feet above its battling neighbors, who had formed a brief alliance to tear it down and destroy the advantage it had wo Despite the fact that this was a silent war, fought, too slowly for the eye see, the impression of merciless, im placable conflict was overwhelming. The plain by comparison, appeared placid and uneventful. It was flat, to within a few inches, right out to the horizon; and seemed to be covered with a thin, wiry grass. Though they descended to within fifty feet of it, there was no sign of any animal life, which hilvar found somewhat surprising. Perhaps, he decided, it had been scared underground by their approach. They hovered just above the plain while alvin tried to convince hilvar that it would be safe open the air lock, and hilvar patiently explained such conceptions as
bacteria, fungi, viruses, and microbes-ideas which alvin found hard to visualize, and harder still to apply to himself. The argument had been in progress for some minutes before they noticed peculiar fact. The vision
screen, which a moment ago ha been showing the forest ahead of them, had no becom blank. "Did you turn that off?" said hilvar, his mind, as usu just on jump ahead of alvin's. "No," replied alvin, a cold shiver running down his spin as he thought of the only other explanation. "Did you turn it off?" he asked the robot. "No," came the reply, echoing his own. With a sigh of reli alvin dismissed the idea that t robot might have started to act on its own volition-then he might have a mechanical mutiny on his hands. "Then why is t screen blank?" he asked. "The image receptors have been covered." "i don't understand," said alvin, forgetting for a m ment that the robot would only a on definite orders or questions. He recovered himself quickly and asked:
"what's covered the receptors?" "i do not know." the literal-mindedness of robots could sometimes be as exasperating as the discursiveness of humans. Before alvin could continue the interrogation hilvar interrupted. "Tell it to lift the ship-slowly," he said, and there was a note of urgency in his voic Alvin repeated the command. There was no sense of mo•tion; there never was. Then, slowly, the image reformed on the vision screen, though for a moment i was blurred and distorted. But it showed enough to end the argument about landing. The level plain was level no longer. A great bulge had formed immediately below them-a bulge which was ripped open at the top where the sh had torn free. Huge pseudopods were waving sluggishly across the gap, as if trying to re•capture the prey that had just escaped from their clutches. As stared in horrified fascination, alvin caught a glimpse of a pulsing scarlet orifice, fringed with whiplike tentacles which were beating in unison, driving anything that came into their reach down into that gaping maw. Foiled of its intended victim, the creature sank slowly into the ground-and it was then tha

alvin realized that the plain below was merely the thin scum on the surface a stagnant sea. "What was that-thing?" he gasped. "I'd have to go down and study it before i could tell you that," hilvar replied matter-of-factly. "It may have been some form of primitive animal-perhaps even a relative of our friend in shalmirane. Certainly it was not intelligent, or it would have know better than to try to eat a spaceship." alvin felt shaken, though he knew t they had been in no possible danger. He wondered what else lived down there beneath that innocent sward, which seemed to positively in•vite him to come
out and run upon its springy surface. "I could spend a lot of time here," hilvar, obviously fascinated by what he had just seen. "Evolution must have produced some very interesting results under these conditions. Not only evolution, but devolution as well, as higher forms of life regressed when the planet was deserted. By now equi•librium must have been reached and-you're not leaving al•ready?" his voice sounded quite plaintive as the landscape receded below them. "I am," said alvin. "I've seen a world with no life, and a wor with too much, and i don't know which i dislike more." five thousand feet above the plain, the planet gave them one final surprise. They encountered a flotilla of huge, flabby balloons drifting down the wind. From each semitransparent envelope clusters of tendrils dangled to form what was
virtually an inverted forest. Some plants, it seemed, in the ef•fort to escap from the ferocious conflict on the surface had learned to conquer the air. B a miracle of adaptation, they had managed to prepare hydrogen and store it i bladders, so that they could lift themselves into the comparative peace. Of
the lower atmosphere. Yet it was not certain that even here they had found se•curity. Their downward-hanging stems and leaves were infested with an
entire fauna of spidery animals, which must! Spend their lives floating far above the surface of the globe, continuing the universal battle for existence on their lonely aerial islands. Presumably they must from time to time have some contact with the ground; alvin saw one of the great balloons suddenly collapse and fall out of the sky, its broken, envelope acting as a crude parachute. He wondered if this was an accident, or part of the life cycle o these strange entities. Hilvar slept while they waited for the next planet to approach. For some reason which the robot could not explain to them, the shi traveled slowly-at least by comparison with its universe-spanning haste-now
that it was within a solar system. It took almost two hours to reach the w that alvin had chosen for his third stop, and he was a little sur•prised th any mere interplanetary journey should last so long. He woke hilvar as they dropped down into the atmosphere "what do you make of that?" he asked, pointing to the vision screen. Below them was a bleak landscape of blacks an gray, showing no sign of vegetation or any other direct evidence of life. Bu there was indirect evidence; the low hills an shallow valleys were dotted wit perfectly formed hemispheres, some of them arranged in complex, symmetrical patterns. They had learned caution on the last planet, and aft carefully considering all the possibilities remained high in the atmosphere while they sent the robot down to investigate. Through its eyes, they saw one of the hemispheres approach until the robot was floating only a few feet awa from t completely smooth featureless surface. There was no sign of any entrance, nor any hint of the pur pose which the structure served. It was quite large- a hundred feet high; some of the other hemispheres we larger still. If it was building, there appeared to be no wa in or out. After some hesitation, alvin ordered the robot to move forward and touch the dome. To his utter astonishment, it refused to obey him. This indeed was mutiny-or so at sight it seemed. "Why won't you do what i tell you?" asked alvin, wh he had recovered from his astonishment. "It is forbidden," came the reply. "Forbidden by whom?" "i do not know." "then how-no, cancel that. Was the order built i you?" "no." that seemed to eliminate one possibility. The builders of these domes might well have been the race who made the robot, and might have included this taboo in the machine's original instructions. "When did you receive the order?" asked alvin. "I received it when i landed." alvin turned to hilvar, the light of a new hope burning in his eyes. "There's intelligenc

here! Can you sense it?" "no," hilvar replied. "This place seems as dead to as the first world we visited." "i'm going outside to join the robot. Whatev spoke to it may speak to me." hilvar did not argue the point, though he lo none too happy. They brought the ship to earth a hundred feet away from the dome, not far from the waiting robot, and opened the air lock. Alvin knew t the lock could not be opened unless the ship's brain had already satisfied itself that the atmosphere was breathable. For a moment he thought it had ma a mis•take-the air was so thin and gave such little sustenance to his lungs. Then, by inhaling deeply, he found that he could grasp enough oxygen to survive, though he felt that a few minutes here would be all that be could endure. Panting hard, they walked up to the robot and to the curv•ing wall the enigmatic dome. They took one more step•then stopped in unison as if hit by the same sudden blow. In their minds, like the tolling of a mighty gong, had boomed a single message: Danger. Come no closer. That was all. It wa message not in words, but in pure thought. Alvin was certain that any creature, whatever its level of intelligence, would receive the same warning,
in the same utterly unmistakable fashion-deep within its mind. It was a warning, not a threat. Somehow they knew that it was not directed against them; it was for their own protection. Here, it seemed to say, is something intrinsically dangerous, and we, its makers, are anxious that no one shall be hurt through blundering ignorantly into it. Alvin and hilvar stepped back several paces, and looked at each other, each waiting for the other to say what was in his mind. Hilvar was the first to sum up the position. "I was right, alvin," he said. "There is no intelligence here. That warning is automatic-triggered by our presence when we get too close." alvin nodded in agreement. "I wonder what they were trying to protect," he said.: "there coul be buildings-anything-under these domes." "there's no way we can find out, if all the domes warn us off. It's interesting-the difference between the three planets we've visited. They took everything away from the first-they abandoned the second without bothering about it -but they went to a lot of trouble he Perhaps they expected to come back some day, and wanted everything to be rea for them when they returned." "but they never did-and that was a long time ago." "they may have changed their minds." it was curious alvin thought, how both he and hilvar had unconsciously started using the word "they." whoever o whatever "they" had been, their presence had been strong on that first
planet-and was even stronger here. This was a world that had been carefully wrapped up, and put away until it might be needed again. "Let's go back to ship," panted alvin. "I can't breathe properly here." as soon as the air loc had closed behind them, and they were at ease once more, they discussed thei next move. To. Make a thorough investigation, they should sample a large
number of domes, in the hope that they might find one that had no warning which could be entered. If that failed• alvin would not face that possibility until he had to. He faced it less than an hour later, and in a far more dramatic form than he would have dreamed. They had sent: the robot down to half a dozen domes, always with the same, result, when they came across a scene that was badly out of place on this tidy, neatly packaged world. Below them was a broad valley, sparsely sprinkled with' the tantalizing,
impenetrable domes. At its center was the unmistakable scar of a great explosion-an explosion that had thrown debris for miles in all directions and burned a shallow crater in the ground. And beside the crater was the wreckag of a spaceship. Twenty-one They landed close to the scene of this ancient tragedy and walked slowly, conserving their breath toward mense, broken hull towering above them. Only a short section -either the prow or the stern-of t ship remained; pre•sumably the rest had been destroyed in the explosion. As they approached the wreck, a thought slowly dawned in al•vin's mind, becoming stronger and stronger until it attained the status of certainty. "Hilvar," he said, finding it hard to talk and walk at the same time, "i believe this i the ship that landed on the first planet we visited." hilvar nodded,
preferring not to waste air. The same idea had already occurred to him. It
a good object lesson, he thought, for incautious visitors. He hoped it would

exposed had be
roughly sliced in two; floors and walls and ceil•ings, broken at the point o the explosion, gave a distorted chart of the ship's cross section. What
strange beings, won•dered alvin, still lay where they had died in the wreckag of their vessel? "I don't understand this," said hilvar suddenly. "This
portion of the ship is badly damaged, but it's still fairly in•tact. Where's the rest of it? Did it break in two out in space, and this part crash her not until they had sent the robot exploring again, and had themselves examine the area around the wreckage, did they learn the answer. There was no shadow of doubt; any reservations they might have had were banished when alvin found the line of low mounds, each ten feet long, on the little hill beside the ship. "So they landed here," mused hilvar, "and ignored the warning. They wer inquisitive, just as you are. They tried to open that dome." he pointed to other side of the crater, to the smooth, still unmarked shell within which t departed rulers of this world had sealed their treasures. But it was no long a dome; it was now an almost complete sphere, for the ground in which it h been set had been blasted away. "They wrecked their ship, and many of them were killed. Yet despite that, they managed to make repairs and leave again, cutting off this section and stripping out everything of value. What a task that must have been!" alvin scarcely heard him. He was looking at the curiou marker that had first drawn him to this spot-the slim shaft pinged by a horizontal circle a third of the way down from its up. Alien and unfamiliar though it was, be could respond to the mute message it had carried down the ages. Underneath those stones, if he cared to disturb them, was the answer t one question at least. It could remain unan•swered; whatever these creatures might have been, they had earned their right to rest. Hilvar scarcely heard the words alvin whispered as walked slowly back to the ship. "I hope they g home," he said. "And where now?" asked hilvar, when they were once more out space. Alvin stared thoughtfully at the screen before replying. "Do you think
i should go back?" he said. "It would be the sensible thing to do. Our luc may ad hold out much longer, and who knows what other surprise these planets may have waiting for us?" it was the voice of sanity and caution, and alvin wad now prepared to give it greater heed than he would have done a few day before. But he had come a long way, and waited all his life, for this mome he would not turn bar while there was still so much to see. "We'll stay in ship from now on," he said, "and wn won't touch surface anywhere. That shoul be safe enough surely." hilvar shrugged his shoulders, as if refusing to
accept any responsibility for what migt happen next. Now that alvin was showing a certain amount of caution, he thought it unwise to admit that he equally anxious to continu! Their exploring, though he had long ago abandoned all hopl of meeting intelligent life upon any of these planets. A double wor lay ahead of them, a great planet with 1 smaller satellite beside it. The primary might have been the twin of the second world they had visited; it w clothed it that same blanket of livid green. There would be no point it landing here; this was a story they already knew. Alvin brought the ship low over the surface of the satellite, he needed no warning from the complex mechanism which protected him to know that there was no atmosphere here. Al shadows had a sharp, clean edge, and there were no gradation between night a day. It was the first world on which he had seen something approaching night for only one of the more distant suns was above the horizon in the area wh they made first contact. The landscape was bathed in a dull rep light, as though it had been dipped in blood. For many miles they flew above mountains that were sti) as jagged and sharp as in the distant ages of their birth. This was a world that had never known change or decay, hay never been scour by winds and rains. No eternity circuit were needed here to preserve objects in their pristine fresh ness. But if there was no air, then there could hav been no life -or could there have been? "Of course," said hilvar, when alvin put the question d him, "there's nothing biologically absurd in the idea. Lif can't originate in airless space-but it can evolve forms that will survive in

it. It must have happened millions of times, whenever an inhabited planet los its atmosphere." "but would you expect intelligent life forms to exist in a vacuum ? Wouldn't they have protected themselves against the loss of their air?" "probably, if it occurred after they achieved enough in•telligence to
stop it happening. But if the atmosphere went while they were still in the primitive state, they would have to adapt or perish. After they had adapted, they might then develop a very high intelligence. In fact, they probably
would-the incentive would be so great." the argument, decided alvin, was a purely theoretical one, as far as this planet was concerned. Nowhere was ther any sign that it had ever borne life, intelligent or otherwise. But in that case, what was the purpose of this world? The entire multiple system of the seven suns, he was now certain, was artificial, and this world must be part its grand design. It could, conceivably, be intended purely for ornament to provide a moon in the sky of its giant companion. Even in that case, howeve it seemed likely that it would be put to some use. "Look, said hilvar, pointing to the screen. "Over there, on the right." alvin changed the ship's course, and the landscape tilted around them. The red-lit rocks blurred with the speed of their motion; then the image stabilized, and sweeping below was the unmistakable evidence of life. Unmistakable-yet also baffling. It took the form of a wide-spaced row of slender columns, each a hundred feet from its neighbor and twice as high. They stretched into the distance, dwindling in hypnotic perspective, until the far ho•rizon swallowed them up. Alvin swung
the ship to the right, and began to race along the line of columns, wonderi as he did so what purpose they could ever have served. They were absolutely uniform, marching in an unbroken file over hills and down into val•leys. Ther was no sign that they had ever supported any•thing; they were smooth and featureless, tapering very slight•ly toward the top. Quite abruptly, the line changed its course, turning sharply through a right angle. Alvin overshot by several miles before he reacted and was able to swing the ship around in th new direction. The columns continued with the same unbroken stride across the landscape, their spacing perfectly regular. Then, fifty miles from the last change of course, they turned abrupt•ly through another right angle. At this rate, thought alvin, we will soon be back where we started. The endless sequence of columns had so mesmerized them fat when it was broken they were miles past the discontinuity before hilvar cried out and made alvin, who had noticed nothing, turn the ship back. They descended slowly, and they circled above what hilvar had found, a fantastic picion began to dawn in their
minds-though at first neither dared mention it to the other. Two of the columns had been broken off near their base and lay stretched out upon the rocks where they had fallen. Nor was that all; the two columns adjoining the gap had bent outward by some irresistible force. _ There was no escape from the awesome conclusion. Alvin knew what they had been flying over; it was so thing he had seen often enough in lys, but until this mom the shocking chan of scale had prevented recognition. "Hilvar," he said, still hardly daring to put his thou into words, "do you know what this is?" ` "it seems hard believe, but we've been flying aro the edge of a corral. This thing is a fence-a fence l hasn't been strong enough." "people who keep pets," said
alvin, with the nervous lain men sometimes use to conceal their awe, "should make sure they know how to keep them under control." hilvar did not react t his forced levity; he was staring the broken barricade, his brow furrowed wit thought. "I don't understand it," he said at last. "Where could have got foo on a planet like this? And why did it bred out of its pen? I'd give a lo know what kind of animal was." "perhaps it was left here, and broke out because it ail hungry," alvin surmised. "Or something may have made it annoyed." "let's go lower," said hilvar. "I want to have a look the ground." they decended until the ship was almost touching barren rock, and it was the that they noticed that the ply was pitted with innumerable small holes no mo than an inch or two wide. Outside the stockade, however, the groud was free from these mysterious pockmarks; they stopped ruptly at the line of the fence "You are right," said hilvar. "It was hungry. But it wash an animal: it wou

be more accurate to call it a plant. Had exhausted the soil inside its pen, and had to find fry food elsewhere. It probably moved quite slowly; perhaps took years to break down those posts." alvin's imagination swiftly filled in the details he could never know with certainty. He did not doubt that hilvar analysis was basically correct, and that some botanical monster, perhaps
moving too slowly for the eye to see, had foul a sluggish but relentless battle against the barriers that hemmed it in. It might still be alive, even after all these ages, rovin will over the face of this planet. To look for now, would be a hopeless task, since it would mean quartering the surface of an entire globe. They made a desultory search in the few square miles around the gap, and located one great circular patch of pockmarks almost five hundre feet across. Where the creature had obviously stopped to feed one could apply that word to an organism that somehow drew its nourishment from solid rock. they lifted once more into space, alvin felt a strange weariness come over him. He had seen so much, yet learned so little. There were many wonders on all these planets, but what he sought had fled them long ago. It would be useless, he knew, to visit the other worlds of the seven suns. Even if ther was still intelligence in the universe, where could he seek it now? He looke at the stars scattered like dust across the vision screen, and knew that wha was left of time was not enough to explore them all. A feeling of lonelines and oppression such as he had never before experienced seemed to overwhelm
him. He could un•derstand now the fear of diaspar for the great spaces of t universe, the terror that had made his people gather in the little microcosm of their city. It was hard to believe that, after all, they had been right. turned to hilvar for support. But hilvar was standing, fists tightly clenched and with a glazed look in his eyes. His head was tilted on one side; he s to be listening, strain•ing every sense into the emptiness around them. "What is it?" said alvin urgently. He had to repeat the question before hilvar showed any sign of hearing it. He was still staring into nothingness when he finally replied. "There's something coming," he said slowly. "Something that i don't understand." it seemed to alvin that the cabin had suddenly become very cold, and the racial nightmare of the invaders reared up to confront him in all its terror. With an effort of will that sapped his strength, he forced mind away from panic. "Is it friendly?" he asked. "Shall i run for earth?" hilvar did not answer the first question-only the second. His voice was very faint, but showed no sign of alarm or fear. It held rather a vast astonishm and curiosity, as if he had encountered something so surprising that he could not be bothered to deal with alvin's anxious query. "You're too late," he said. "It's already here." The galaxy had turned many times on its axis si conscious•nness first came to vanamonde. He could recall little of those first aeons and the creatures who had tended him then-but he could remember still his desolation when they had gone and left him alone among the stars. Down ages since, he had wandered from sun to sun, slowly evolving and increasing iiis powers. Once he had dreamed of finding again those who had attended his birth, and though the dream had faded it had never wholly died. On countless worlds he had found the wreckage that it had left behind, but intelligence h had discovered only once -and from the black sun he had fled in terror. Yet the universe was very large, and the search had scarcely begun. Far away though it was in space and time, the great burst of power from the heart o the galaxy beckoned to vas monde across the light-years. It was utterly unlik the radiation of the stars, and it had appeared in his field of a consciousness as suddenly as a meteor trail across a cloudy sky. He moved through space and time toward it, to the lab moment of its existence, sloughing from him in the way he knew the dead, unchanging pattern of the past. The long metal shape, with its infinite complexities structure, he could not understand, for it was as strap to him as almost all the things of the physical world. Arou it still clung the aura of power that had drawn him ac the universe, but that was of no interest to him now. Cap fully, with the delicate nervousness of a wild beast half poi for flight, he reached out toward the two minds he had, covered. And then he knew that his long search

was ended. Alvin grasped hilvar by the shoulders and shook him violently, trying to drag him back to a greater awareness reality. "Tell me what's happening!" he begged. "What do you want me to do?" the remote, abstracted look slowly faded from hilvars eyes. "I still don't understand," he said, "bu there's no need to be frightened-i'm sure of that. Whatever it is, it wok h us. It seems simply-interested." alvin was about to reply when he was suddenl overwhelmed by a sensation unlike any he had ever known fore. A warm, tingli glow seemed to spread through body; it lasted only a few seconds, but when was gone was no longer merely alvin. Something was sharing his brain, overlapping it as one circle may partly cover another. He was conscious, also of hilvar's mind close at hand, equally entangled in whatever creature had descended upon th the sensation was strange rather than unpleasant, and it alvin his first glimpse of true telepathy-the power which his people had so degenerated that it could now be used to control machines. Alvin had rebelled at once when seranis had tried dominate his mind, but he did not struggle against this trusion. It would have been useless, and he knew that creature, whatever it might be, was not unfriendly. He let himself relax, accepting without resistance the fact that infinitely greater intelligence than his own was exploring his mind. But in that belief, he was not wholly right. One of these minds, vanamonde saw at once, was more apathetic and accessible than th other. He could tell that both were filled with wonder at his presence, and that sur•prised him greatly. It was hard to believe tat they could have forgotten; forgetfulness like mortality, was beyond the comprehension of vanamonde. Communication was very difficult; many of the thought•images in
their minds were so strange that he could hardly recognize them. He was puzzled and a little frightened by the recurrent fear pattern of the invaders it reminded him of his own emotions when the black sun first came into his field of knowledge. But they knew nothing of the black sun, and now their o questions were beginning to form in his mind. "What are you?" he gave the o reply he could. "I am vanamonde." there came a pause (how long the pattern their thoughts took to form!) and then the question was repeated. They had n understood; that was strange, for surely their kind had given him his name f it to be among the memories of his birth. Those memories were very few, and they began strangely at a single point in time, but they were crystal clear. Again their tiny thoughts struggled up into his conscious•ness. "Where are the people who built the seven suns? What happened to them?" he did not know; t could scarcely believe him, and their disappointment came sharp and clear
across the abyss separating their minds from his. But they were patient and was glad to help them, for their quest was the same as his and they gave the first companionship be had ever known. As long as he lived, alvin did n believe he would ever again undergo so strange an experience as this soundles conversation. It was hard to believe that he could be little more than a spectator, for he did not care to admit, even to himself, that hilvar's mind was in some ways so much more capable than his own. He could only wait and wonder, half dazed by the torrent of thought just beyond the limits of his understanding. Presently hilvar, rather pale and strained, broke off the
contact and turned to his friend. "Alvin," he said, his voice very tired. "There's something strange here. I don't understand it at all." the news did little to restore alvin's self-esteem and his face must have shown his feelings, for hilvar gave a sudden, sympathetic smile. I can't discover what this-vanamonde-is," he continued. "It's a creature of tremendous knowledge,
but it seems to have very little intelligence. Of course," he added, "its mi may be of such a different order that we can't understand it-yet somehow i don't believe that is the right explanation." "well, what have you learned?" asked alvin with some impatience. "Does it know anything about the seven
suns?" hilvar's mind still seemed very far away. "They were built by many races, including our own," he said absently. "It can give me facts like that but it doesn't seem to understand their meaning. I believe it's conscious of the past, without being able to interpret it. Everything that's ever happened seems jumbled together in its mind." he paused thoughtfully for a moment; the

his face light•ened. "There's only one thing to do; somehow or other, we mus get vanamonde to earth so that our philosophers can study him." "would that safe?" asked alvin. "Yes," answered hilvar, thinking how uncharacteristic his friend's remark was. "Vanamonde is friendly. More than that, in fact, he seem almost affectionate." and quite suddenly the thought that all the while had been hovering at the edge of alvin's consciousness came clearly into view. He remembered krif and all the small animals that were constantly escaping, to
the annoyance or alarm of hilvar's friends. And he recalled-how long ago that seemed!-the zoological purpose behind their expedition to shalmirane. Hilvar
had found a new pet. Twenty-two How completely unthinkable, jeserac mused, this conference would have seemed only a few short days ago. The six visitor from lys sat facing the council, along a table placed across the open end o the horseshoe. It was ironic to remember that not long ago alvin had stood the same spot and heard the council rule that diaspar must be closed again from the world. Now the world had broken in upon it with, a vengeance and only the world, but the universe. The council itself had already changed. No less than five of its members were missing. They had been unable to face: t responsibilities and problems now confronting them, and had followed the path that khedron had already taken. It was, thought jeserac , proof that diaspar had failed if so many of its citizens were unable to face their first real chal•lenge in millions of years. Many thousands of them had al•ready fled int the brief oblivion of the memory banks, hop•ing that when they awoke the crisis would be past and diaspar would be its familiar self again. They woul be disappointed. Jeserac had been co-opted to fill one of the vacant places the council. Though he was under something of a cloud, owing to his position as alvin's tutor, his presence was so obviously essential that no one had suggested excluding him. He sat at one end of the horseshoe-shaped table-a position which gave him several advantages. Not only could he study the profiles of his visitors but he could also see the faces of his fellow councilors-and their expressions were sufficiently instructive. There was no
doubt that alvin had been right, and the council was slowly realizing the unpalatable truth. The dele•gates from lys could think far more swiftly than the finest minds in diaspar. Nor was that their only advantage, for they als showed an extraordinary degree of co-ordination which jeserac guessed must be due to their telepathic powers. He wondered if they were reading the councilors' thoughts, but decided that they would not have broken the solemn as•surance without which this meeting would have been impos•sible. Jeserac did not think that much progress had been made; for that matter, he did not see how it could have been made. The council, which had barely accepted the existence of lys, still seemed incapable of realizing what had happened. But
it was clearly frightened-and so, he guessed, were the visi•tors, though they managed to conceal the fact better. Jeserac himself was not as terrified as had expected; his fears were still there, but he had faced them at last. Some•thing of alvin's own recklessness-or was it courage?-had begun to change his outlook and give him new horizons. He did not believe he would ever be able to set foot beyond the walls of diaspar, but now he understood the impulse that had driven alvin to do so. The president's question caught him unawares, but he re•covered himself quickly. "I think," he said, "that it was sheer chance that this situa•tion never arose before. We know that there were fourteen earlier uniques, and there must have been some definite plan behind their creation. That plan, i believe, was to in•sure that lys and diaspar would not remain apart forever. Alvin had seen to that, but he has also don something which i do not imagine was ever in the original scheme. Could the central computer confirm that?" the impersonal voice replied at once. "The councillor knows that i cannot comment on the instructions given to me by my designers" jeserac accepted the mild reproof. "Whatever the cause, we cannot dispute the facts. Alvin has gone out into space. When he returns, you may prevent him leaving again-though i doubt if you will succeed, for he may hav learned a great deal by then. And if what you fear has happened, there is nothing any of us can do about it earth is utterly helpless-as she has been

for millions of cen•turies." jeserac paused and glanced along the tables. His words had pleased no one, nor had he expected them to do so. "Yet i don't why we should be alarmed. Earth is in no greater danger now than she has always been. Why should two men in a single small ship bring the wrath of invaders down upon us again? If we'll be honest with ourselves, we must admi that the invaders could have destroyed our world ages ago." there was a disapproving silence. This was heresy-and once jeserac himself would have condemned it as such. The president interrupted, frowning heavily. "Is there
not a legend that the invaders spared earth itself only on condition that ma never went into space again? And have we not now broken those conditions?" " legend, yes," said jeserac. "We accept many things without question, and this is one of them. However, there is no proof of it. I find it bard to belie that anything of such importance would not be recorded in the memories of th central computer, yet it knows nothing of this pact. I have asked it, though only through the information machines. The council may care to ask the
question directly." jeserac saw no reason why he should risk a second admon•ishment by trespassing on forbidden territory, and waited for the president's reply. It never came, for in that moment the visitors from lys suddenly started in their seats, while their faces froze in simultaneous expressions of incredulity and alarm. They seemed to be listening while some faraway voice poured its message into their ears. The councilors waited, their own apprehension growing minute by minute as the soundless conversation
proceede then the leader of the delegation shook himself free from his trance and turned apologetically to the president. "We have just had some very
strange and disturbing news from lys," he said. "Has alvin returned to earth? asked the president. "No-not alvin. Something else." As he brought his faithful ship down in the glade of airlee, alvin wondered if ever in human history any ship had brought such a cargo to earth-if, indeed, vanamonde was located in the physical space of the machine. There had been no sign of him the voyage; hilvar believed, and his knowl•edge was more direct, that only vanamode's sphere of at•tention could be said to have any position in space. Vana•monde himself was not located anywhere-perhaps not even anywhen. Seranis
and five senators were waiting for them as they emerged from the ship. One the senators alvin had al•ready met on his last visit; the other two from t pre•vious meeting were, he gathered, now in diaspar. He won•dered how the delegation was faring, and how the city had reacted to the presence of the first intruders from outside in so many millions of years. "It seems, alvin," said seranis drily, after she had greeted her son, "that you have a genius discovering remarkable entities. Still, i think it will be some time before
you can sur•pass your present achievement." for once, it was alvin's turn to be surprised. "Then vanamonde's arrived?" "yes, hours ago. Somehow he managed
to trace the path your ship made on its outward journey-a staggering feat in itself, and one which raises interesting philosophical prob•lems. There is
some evidence that he reached lys at the mo•ment you discovered him, so that he is capable of infinite speeds. And that is not all. In the last few hou he has taught us more of history than we thought existed." alvin looked at
in amazement. Then he understood; it was not hard to imagine what the impact of vanamonde must have been upon this people, with their keen perceptions and their wonderfully interlocking minds. They had reacted with surprising speed,
and he had a sudden incongruous pic•ture of vanamonde, perhaps a little frightened, surrounded by the eager intellects of lys. "Have you discovered what he is?" alvin asked. "Yes. That was simple, though we still don't know
his origin. He's a pure mentality and his knowledge seems to be unlimited. B
he's childish, and i mean that quite liter•ally." "of course!" cried hilvar. "I should have guessedl" alvin looked puzzled, and seranis took pity on him. "I mean that although vanamonde has a colossal, per•haps an infinite mind,
he's immature and undeveloped. His actual intelligence is less than that of a human being"-she smiled a little wrylyr-"though his thought processes are much faster and he learns very quickly. He also has some powers we do not yet understand. The whole of the past seems open to his mind, in a way that's

difficult to describe. He may have used that ability to follow your path bac to earth." alvin stood in silence, for once somewhat overcome. He realized ho right hilvar had been to bring vanamonde to lys. And he knew how lucky he been ever to outwit seranis; that was not something he would do twice in a life•time. "Do you mean," he asked, "that vanamonde has only just been born?" "by his standards, yes. His actual age is very great, though apparently less than man's. The extraordinary thing is that he insists that we created him, and there's no doubt that his origin is bound up with all the great mysteri of the past." "what's happening to vanamonde now?" asked hilvar in a slightly possessive voice. "The historians of grevarn are questioning him. They are trying to map out the main outlines of the past, but the work will take ye Vanamonde can describe the past in per•fect detail, but as he doesn't understand what he sees it's very difficult to work with him." ' alvin wondered how seranis knew all this; then he re•alized that probably every waking mind in lys was watch•ing the progress of the great research. He felt sense of pride in the knowledge that he had now made as great a a mark on as on diaspar, yet with that pride was mingled frustration. Here was somethin that he could never fully , share nor understand: the direct contact even between hu•man minds was as great a mystery to him as music must be to a man or color to a blind one. Yet the people of lys were now exchanging thoughts with this unimaginably alien being, whom he had led to earth but wh he could never detect with any sense that he possessed. There was no place him here; when the inquiry was, finished, he would be told the answers. He opened the gates of infinity, and now felt awe-even fear-for all that he had done. For his own peace of mind, he must return to the tiny, familiar world diaspar, seeking its shelter while he came to grips with his dreams and his ambition. There was irony here; the one who had spurned the city to venture out among the stars was coming home as a frightened child runs back to its mother. Twenty-three Diaspar was none too pleased to see alvin again. The city was still in a ferment, like a giant beehive that had been violently stirred with a stick. It was still reluctant to face reality, but those who refused to admit the existence of lys and the outside world no longer had a place to hide. The memory banks had ceased to accept them; those who tried cling to their dreams, and to seek refuge in the future, now walked in vain into the hall of creation. The dissolving, heatless flame refused to greet them; they no longer awoke, their minds washed clean, a hundred thousand year further down the river of time. No appeal to the central computer was of an avail, nor would it explain the reason for its actions. The intended refugees had to turn sadly back into city, to face the problems of their age. Alvin hilvar had landed at the periphery of the park, not far from council hall. Until the last moment, alvin was not certain that he could bring the ship i the city, through whatever screens fenced its sky from the outer world. The firmament of diaspar, like all else about it, was artificial, or at least partly so. Night, with its starry reminder of all that man had lost, was ne allowed to intrude upon the city; it was protected also from the storms that sometimes raged across the desert and filled the sky with moving walls of sand. The invisible guardians let alvin pass, and as diaspar lay spread out beneath him, he knew that he had come home. However much the universe and i mysteries might call him, this was where he was born and where he belonged. would never satisfy him, yet always he would return. He had gone halfway across the galaxy to learn this simple truth. The crowds had gathered even before the ship landed, and alvin wondered how his fellow citizens would receive him now that he had returned. He could read their faces easily enoug as he watched them through the viewing screen be•fore he opened the air lock The dominant emotion seemed to be curiosity-in itself something new in
diaspar. Mingled with that was apprehension, while here and there were un•mistakable signs of fear. No one, alvin thought a little wist•fully, seemed glad to see him back. The council, on the other hand, positively welcomed hi
-though not out of pure friendship. Though he had caused this crisis, he alo could give the facts on which future policy must be based. He was listened

with deep attention as he described his flight to the seven suns and his meeting with vanamonde. Then he answered innumerable questions, with a
patience which probably surprised his interrogators. Uppermost in their minds, he quickly discovered, was the fear of the invaders, though they never mentioned the name and were clearly unhappy when he broached the subject di•rectly. "If the invaders are still in the universe," alvin told the council, "then surely i should have met them at its very center. But there no intelligent life among the seven suns; we had already guessed that before vanamonde confirmed it. I believe that the invaders departed ages ago; certainly vanamonde, who appears to be at least as old as diaspar, knows
nothing of them." "I have a suggestion," said one of the councilors suddenl "Vanamonde may be a descendant of the invaders, in some way beyond our prese understanding. He has forgotten his origin, but that does not mean that one day he may not be dangerous again." hilvar, who was present merely as a spectator, did not wait for permission to speak. It was the first time that alvin had ever seen him angry. "Vanamonde has looked into my mind," he said, "and i have glimpsed something of his. My people have already learned much about him, though they have not yet discovered what he is. But one thing is certain-he is friendly, and was glad to find us. We have nothing to fear fr him." there was a brief silence after this outburst, and hilvar relaxed with somewhat embarrassed expression. It was no•ticeable that the tension in the council chamber lessened from then on, as if a cloud had lifted from the spirits of those present. Certainly the president made no attempt, as he was supposed to do, to censure hilvar for his interruption. It was clear to alvi as he listened to the debate, that three schools of thought were represented on the council. The conservatives, who were in a minority, still hoped that the clock could be turned back and that the old order could somehow be restored. Against all reason, they clung to the hope that diaspar and lys could be persuaded to forget each other again. The progressives were an
equally small minority; the fact that there were any on the council at all pleased and surprised alvin. They did not exactly welcome this invasion of th out•er world, but they were determined to make the best of it. Some of them went so far as to suggest that there might be a way of breaking through th psychological barriers which for so long had sealed diaspar even more effectively than the physical ones. Most of the council, accurately reflecting the mood of the city, had adopted an attitude of watchful caution, while the waited for the pattern of the future to emerge. They realized.. That they could make no general plans, nor try to carry out any definite policy, until the storm had passed. Jeserac joined alvin and hilvar when the session was over. He seemed to have changed since they had last met-and last parted-in t tower of loranne, with the desert spread out beneath them. The change was no one that alvin had expected, though it was one that he was to encounter mor and more often in the days to come. Jeserac seemed younger, as if the fires life had found.1 fresh fuel and were burning more brightly in his veins. De•spite his age, he was one of those who could accept the challenge that alvin had thrown to diaspar. "I have some news for you, alvin," he said. "I think you know senator gerane." alvin was puzzled for a moment; then he remembered. "Of course-he was one of the first men i met in lys. Isn't he member of their delegation?" "yes, we have grown to know each other quite well. He is a brilliant man, and understands more about the human mind than would have believed possible-though he tells me that by the standards of lys he is only a beginner. While he is here, he is starting a project which wi be very close to your heart. He is hoping to analyze the compulsion which keeps us in the city, and he believes that once he has discovered how it w imposed, he will be able to remove it. About twenty of us are already
co-operating with him." "and you are one of them?" "yes," replied jeserac, showing the nearest approach to bashfulness that alvin had ever seen or ever would see. "It is not easy, and certainly not pleasant-but it is stimulating. "how does gerane work?" "he is operating through the sagas. He has had a wh series of them constructed, and studies our reactions when we are experiencing

them. I never thought, at my age, that i should go back to my childhood recreations again" "what are the sagas?" asked hilvar. "Imaginary dream worlds," exclaimed alvin. "At least, most of them are imaginary, though some
are probably based on historical facts. There are millions of them recorded i the memory cells of the city; you can take your choice of any kind of adventure or experience you wish, and it will seem utterly real to you while the impulses are being fed into your mind." he turned to jeserac. "What kind of sagas does gerane take you into?" "most of them are concerned, as you mi expect, with leaving diaspar. Some have taken us back to our very earliest lives, to as near to the founding of the city as we can get. Gerane believ that the closer he can get to the origin of this compulsion, the more easil he will be able to undermine it." alvin felt very encouraged by this news. work would be merely half accomplished if he had opened the gates of
diaspar-only to find that no one would pass through them. "Do you really wan to be able to leave diaspar?" asked hilvar shrewdly. "No," replied jeserac, without hesitation. "I am terrified of the idea. But i realize that we were completely wrong in thinking that diaspar was all the world that mattered, an logic tells me that something has to be done to rectify the mistake. Emotionally, i am still quite incapable of leaving the city; perhaps i always shall be. Gerane thinks he can get some of us to come to lys, and i am w to help him with the experiment-even though half- the time i hope that it w fail" alvin looked at his old tutor with a new respect. He no longer discounted the power of suggestion, nor underesti•mated the forces which could compel a man to act in de•fiance of logic. He could not help comparing jeserac's calm courage with khedron's panic flight into the future,-though
with his new understanding of human nature he no longer cared to condemn the jester for what he had done. Gerane, he was certain, would accomplish what h had set out to do. Jeserac might be too old to break the pattern of a lifetime, however willing he might be to start afresh. That did not matter, for others would succeed, with their skilled guidance of the psychologists of lys. And once a few" had escaped from their billion-year-old mold, it would only be a question of time before the remainder could follow. He wondered wh would happen to diaspar and to lys when the barriers were fully down. Someho the best ele•ments of both must be saved, and welded into a new and healthi culture. It was a terrifying task, and would need all the wisdom and all th patience that each could bring to bear. Some of the difficulties of the forthcoming adjustments: had already been encountered. The visitors from lys
had, politely enough, refused to live in the homes provided for them in the city. They had set up their own temporary ac•commodation in the park, among surroundings, which re•minded them of lys. Hilvar was the only exception; though he disliked living in a house with indeterminate walls and ephemeral furniture, he bravely accepted alvin's hospitality, reassured by the promise
that they would not stay here for long. Hilvar had never felt lonely in his life, but he knew lone•liness in diaspar. The city was stranger to him than lys had, been to alvin, and he was oppressed and overwhelmed by its infinite complexity and by the myriads of strangers who seemed to crowd every inch of space around him. He knew, if only in a tenuous manner, everyone in lys, whether he had met them or not. In a thousand lifetimes he could never know everyone in diaspar, and though he realized that this was and irrational feeling, it left him vaguely depressed. Only his loyalty to alvin held him here in a world that had nothing in common with his own. He had often trie analyze his feelings toward alviti. His friendship sprang, he knew, from the same source th inspired his sympathy for all small and struggling creatur thi would have astonished those who thought of alvin as willful, stubborn, and
self-centered, needing no affection from anyone and incapable of returning it even if it was offered. Hilvar knew better than this; he had sensed it instinctive even from the first. Alvin was an explorer, and all explor are seeking something they have lost. It is seldom that they find it, and more seldom still that the attainment brings them greater happiness than the quest. What alvin was seeking, hilvar did not know. He was driven by forces that h

been set in motion ages before, by the men of genius who planned diaspar wi such perverse skill •or by the men of even greater genius who had opposed them. Like every human being, alvin was in some measure a ma•chine, his actions predetermined by his inheritance. That did not alter his need for understanding and sympathy, nor did it render him immune to loneliness or frustration. To his own people he was so unaccountable a creature that they some•times forgot that he still shared their emotions. It needed a stranger from a totally different environment to see him as another human being. Withi a few days of arriving in diaspar, hilvar had met more people than in his entire life. Met them-and had grown to know practically none. Because they
were so crowded together, the inhabitants of the city maintained a reserve
that was hard to penetrate. The only privacy they knew was that of the mind and they still clung to this even as they made their way through the endles social activities of dias•par. Hilvar felt sorry for them though he knew that they felt no need for his sympathy. They did not realize what they were missing-they could not understand the warm sense of community, the feeling of belonging which linked every•one together in the telepathic society of lys. Indeed, though they were polite enough to try to conceal it, it was obvious that most of the people he spoke to looked upon him pityingly as leading an incredibly dull and drab existence. Eriston and etania, alvin's guardians,
hilvar quickly dis•missed as kindly but totally baffled nonentities. He found
it very confusing to hear alvin refer to them as his father and mother-words which in lys still retained their ancient bio•logical meaning. It required a continual effort of imagination to remember that the laws of life and death had been re•pealed by the makers of diaspar, and there were times when it seemed to hilvar that despite all the activity around him, the city was half empty because it had no children. He wondered what would happen to diaspar n that its long isolation was over. The best thing the city could do, he decided, was to destroy the memory banks which had held it entranced for so many ages. Miraculous though they were-perhaps the supreme triumph of the science that had produced them-they were the creations of a sick culture, a culture that had been afraid of many things. Some of those fears had been based on reality, but others, it now seemed, lay only in the imagination. Hilvar knew a little of the pattern that was beginning to emerge from the exploration of vana•monde's mind. In a few days, diaspar would know it
too-•and would discover how much of its past had been a myth. Yet if the memory banks- were destroyed, within a thousand years the city would be dead, since its people had lost the power to reproduce themselves. That was the dilemma that had to be faced, but already hilvar had glimpsed one possible solution. There was always an answer to any techni•cal problem, and his peopl were masters of the biological sciences. What had been done could be undone, if diaspar so wished. First, however, the city would have to learn what it had lost. Its education would take many years-perhaps many a
centuries. But it was beginning; very soon the impact of the first lesson would shake diaspar as profundly as had contact with lys itself. It would shake lys too. For all the difference between the two cultures, they had sprung from the same roots-and they had shared the same illusions. They would both be healthier when they looked once more, with a calm and steadfast gaze into the past which they had lost. Twenty-four The amphitheater had been designed to hold the entire waking population of diaspar, and scarcely one of its ten million places was empty. As he looked down the great curving sweep from his vantage point high up the slope, alvin was irresistibly reminded of shalmirane. The two craters were of the same shape, and almost the same size If one packed the crater of shalmirane with humanity, it would look very muc like this. There was, however, one fundamental difference between the two. The great bowl of shalmirane existed; this amphi•theater did not. Nor had it ever done so; it was merely a phantom, a pattern of electronic charges, slumbering in the memory of the central computer until the need came to call it forth. Alvin knew that in reality he was still in his room, him and that all the myriads of people who appeared to surround him were equally in their own

homes. As long as he made no attempt to move from this spot, the illusion perfect. He could believe that diaspar had been abolished and that all. Its citizens had been assembled here in this enormous cavity. Not once in a thousand years did the life of the city stop. So that all its people could meet in grand assembly. In lys" also. Alvin knew, the equivalent of this gathering was taking place. There it would be a meeting of minds, but perhap as•sociated with it would be an apparent meeting of bodies, as imaginary yet as seemingly real as this. He could recognize most of the faces around him, out to the limits of unaided vision. More than a mile away, and a thousand feet below, was the little circular stage upon which the attention of the entire world was now fixed. It was hard to believe that he could see anythi from such a distance, but alvin knew that when the address began, he would hear and observe everything that happened as clearly as anyone else in
diaspar. The stage filled with mist; the mist became callitrax, lead•er of th group whose task it had been to reconstruct the past from the information which vanamonde had brought to earth. It had been a stupendous, almost an impossible under•taking, and not merely because of the spans of time involved. Only once, with the mental help of hilvar, had alvin been given a brief glimpse into the mind of the strange being they had discovered-or who had discovered them. To alvin, the thoughts of vanamonde were as meaningless as a thousand voices shouting together in some vast, echoing cave. Yet the men of lys could disentangle them, could record them to be analyzed at leisure. Already, so it was rumored-though hilvar would neither deny nor confirm
this-what they had discovered was so strange that it bore scarcely any resem•blance to the history which all the human race had accepted for a billion years. Callitrax began to speak. To alvin, as to everyone else in diaspar, the clear, precise voice seemed to come from a point only a few inches away. Then, in a manner that was hard to define, just as the geometr of a dream defies logic yet rouses no surprise in the mind of the dreamer, alvin was standing beside callitrax while at the same time he retained his posi•tion high up on the slope of the amphitheater. The paradox did not puzz him; be simply accepted it without question, like all the other masteries ove time and space which science had given him. Very briefly, callitrax ran
through the accepted history of the race. He spoke of the unknown peoples of the dawn civilizations, who had left behind them nothing but a hand•ful of great names and the fading legends of the empire. Even at the beginning, so the story went, man had desired the stars-and had at last attained them. For millions of years he had expanded across the galaxy, gathering system after system beneath his sway. Then, out of the darkness be•yond the rim of the universe, the invaders had struck and wrenched from him all that he had won. The retreat to the solar system had been bitter and must have lasted many ages. Earth itself was barely saved by the fabulous battles that raged around shalmirane. When all was over, man was left with only his memories and the world on whih he had been born. Since then, all else had been long-drawn anticlimax. As an ultimate irony, the race that had hoped to rule the univer had abandoned most of its own tiny world, and had split into the two isolat cultures of lys and diaspar-oases of life in a desert that sundered them as effectively as the gulfs be•tween the stars. Callitrax paused; to alvin, as t everyone in the great as•sembly, it seemed that the historian was looking directly at him with eyes that had witnessed things which even now they coul not wholly credit. "So much," said callitrax, "for the tales we have believed since our records began. I must tell you now that they are false-false in every detail-so false that even now we have not fully reconciled them with t truth." he waited for the full meaning of his words to strike home. Then, speaking slowly and carefully, he gave to both lys and diaspar the knowledge that had been won from the a mind of vanamonde. It was not even true that had reached the stars. The whole of his little empire was bounded by the orbits of pluto and persephone, for interstellar space proved a barrier beyond his power to cross. His entire civilization was huddled around the sun, and was still very young when-the stars reached him. The impact must have been

shattering. Despite his failures, man had never doubted that one day he would conquer the depths of space. He believed too that if the universe held his equals, it did not hold his superiors. Now he knew that both beliefs were wrong, and that out among the stars were minds far greater than his own. Fo many centuries, first in the ships of other races and later in machines buil with borrowed knowledge, man had explored the galaxy. Everywhere he found cultures he could understand but could not match, and here and there he encountered minds which would soon have passed altogether beyond his comprehension. The shock was tremendous, but it proved the making of the race Sadder and infinitely wiser, man had returned to the solar system to brood upon the knowledge he had gained., he would accept the challenge, and slowly he evolved a plan which gave hope for the future. Once the physical sciences had been man's greatest in•terest. Now he turned even more fiercely to
genetics and the study of the mind. Whatever the cost, he would drive him•se to the limits of his evolution. The great experiment had consumed the entire energies of the race for millions of years. All that striving, all that sacrifice and toil, became only a handful of words in cal•litrax's narrative. It had brought man his greatest victories. He had banished disease; he could live forever if he wished, and in mastering telepathy he had bent the most subtle of all powers to his will. He was ready to go out again, relying up his own re•sources, into the great spaces of the galaxy. He would meet as a equal the races of the worlds from which he had once turned aside. And he would play his full part in the story of the universe. These things he did. From this age, perhaps the most spacious of all history, came the legends of the empire. It had been an empire of many races, but this had been for•gott in the drama, too tremendous for tragedy, in which it had come to its end. empire had lasted for at least a million years. It must have known many crises, perhaps even wars, but all these were lost in the sweep of great ra moving together toward maturity. "We can be proud," continued callitrax, "of
the part our ancestors played in this story. Even when they had reached thei cultural plateau, they lost none of their initiative. We deal now with conjecture rather than proved fact, but it seems certain that the experiments which were at once the empire's downfall and its crowning glory were inspired and directed by man. "The philosophy underlying these experiments appears to have been this. Contact with other species had shown man how profoundly a race's world-picture depended upon its physical body and the sense organs with which it was equipped. It was argued that a true picture of the universe co be attained, if at all, only by a mind that was free from such physical limitations-a pure mentality, in fact. This was a conception common among many of earth's ancient re•ligious faiths, and it seems strange that an idea which had no rational origin should finally become one of the greatest goals of science. "No disembodied intelligence had ever been encountered in the natural universe; the empire set out to create one. We have forgotten, with so much else, the skills and knowledge that made this possible. The scientists of the empire had mas•tered all the forces of nature all the secrets of time and space. As our mind's are the by-product of an immensely intricate ar•rangement of brain cells, linked together by the network of the nervous system, so the strove to create a brain whose components were not material, but patterns embossed upon space itself. Such a brain if one can call it that, would use elec•trical or yet higher forces for its operation, and would be com•pletely free from the tyranny of matter. It could function with far greater speed th any organic intelligence; it could endure as long as there was an erg of fr energy left in the universe, and no limit could be seen for its powers. Onc created, it would develop potentialities which even its makers could not foresee. "Largely as a result of the experience gained in his own regeneration, man suggested that the creation of such beings should be attempted. It was the greatest challenge ever thrown out to intelligence in
the universe, and after centuries of de•bate it was accepted. All the races the galaxy joined to•gether in its fulfillment. "More than a million years were to separate the dream from the reality. Civilizations were to rise and

fall, again and yet again the age-long toil of worlds was to be lost, but goal was never forgotten. One day we may know the full story of this, the greatest sustained effort in all history. To•day we only know that its ending was a disaster that almost wrecked the galaxy. "Into this period vanamonde's mind refuses to go. There is a narrow region of time which is blocked to h but only, we believe, by his own fears. At its beginning we can see the em at the summit of its glory, taut with the expectation of coming success. At its end, only a few thousand years later, the empire is shattered and the stars themselves are dimmed as though drained of their power. Over the galaxy hangs a pall of fear, a fear with which is linked the name: 'the mad mind. "what must have happened in that short period is not hard to guess. The pur mentality had been created, but it was either insane, or as seems more likel from other sources, was implacably hostile to matter. For centuries it ravaged the universe until brought under control by forces at which we cannot guess. Whatever weapon the empire used in its extremity squandered the resources of the stars; from the memories of that conflict spring some, though not all, o the legends of the invaders. But of this i shall presently say more." "the mind could not be destroyed, for it was im•mortal. It was driven to the edg of the galaxy and there imprisoned in a way we do not understand. Its priso was a strange artificial star known as the black sun, and there it remains this day. When the black sun dies, it will be free again. How far in the future that day lies there is no way of telling." callitrax became silent, a if lost in his own thoughts, ut•terly unconscious of the fact that the eyes all the world were upon him. In the long silence, alvin glanced over the packed multitude around him, seeking to read their minds as they faced this revelation-and this unknown threat which must now replace the myth of the invaders. For the most part, the faces of his fellow citizens were frozen in disbelief; they were still struggling to reject their false past, and could
not yet accept the yet stranger reality that had superseded it. Callitrax
began to speak again in a quiet, more subdued voice as he described the las days of the empire. This was the age alvin realized as the picture unfolded before him, in which he would have like to have lived. There had been adventure then, and a superb and dauntless courage-the courage that could
snatch victory from the teeth of disaster. "Though the galaxy had been laid waste by the mad mind, the resources of the empire were still enormous, and its spirit was unbroken. With a courage at which we can only marvel, the gr experiment was resumed and a search made for the flaw that had caused the catastrophe. There were now, of course, many who opposed the work and
predicted further disasters, but they were overruled. The project went ahead and, with the knowledge so bitterly gained, this time it suc•ceeded. "The new race that was born had a potential intellect that could not even be measured But it was completely infantile; we do not know if this was expected by its creators, but it seems likely that they knew it to be inevitable. Millions o years would be needed before it reached maturity, and noth•ing could be done to hasten the process. Vanamonde was the first of these minds; there must be others elsewhere in the galaxy, but we believe that only a very few were created, for vanamonde has never encountered any of his fellows. "The creation of the pure mentalities was the greatest achievement of galactic civilization; in it man played a major and perhaps a dominant part. I have made no refer to earth itself, for its story is merely a tiny thread in an enor•mous tapestry. Since it had always been drained of its most adventurous spirits,
our planet had inevitably become highly conservative, and in the end it opposed the scientists who created vanamonde. Certainly it played no part at all in the final act." "the work of the empire was now finished; the men o that age looked around at the stars they had ravaged in their desperate peri and they made their decision. They would leave the universe to vanamonde. "There is a mystery here-a mystery we may never solve, for vanamonde cannot help us. All we know is that the em•pire made contact with-something-very strange and very great, far away around the curve of the cosmos, at the oth extremity of space itself. What it was we can only guess, but its call must

have been of immense urgency, and immense promise. Within a very short period of time our ancestors and their fellow races have gone upon a journey which cannot follow. Vanamonde's thoughts seem to be bounded by the confines of the galaxy, but through his mind we have watched the beginnings of this great an mysterious adven•ture. Here is the image that we have reconstructed; now you are going to look more than a billion years into the past-" A pale wraith its former glory, the slowly turning wheel of the galaxy hung in nothingness. Throughout its length were the great empty rents which the mad mind had torn wounds that in ages to come the drifting stars would fill. But they would never replace the splendor that had gone. Man was about to leave his univers as long ago he had left his world. And not only man, but the thousand othe races that had worked with him to make the empire. They were gathered together, here at the edge of the galaxy, with its whole thickness between them and the goal they would not reach for ages. They had assembled a fleet before which imagination quailed. Its flagships were suns its smallest
vessels, planets. An entire globular cluster, with all its solar systems and all their teeming worlds, was about to be launched across infinity. The long line of fire smashed through the heart of the universe, leaping from star to star. In a moment of time a thousand suns had died, feeding their energies the mon•strous shape that had torn along the axis of the galaxy, and was no receding into the abyss.... "So the empire left our universe, to meet its destiny else•where. When its heirs, the pure mentalities, have reached their full stature, it may return again. But that day must still lie far ahead. "This, in its briefest and most superficial outlines, is the story of galacti civilization. Our own history, which to us seems so important, is no more th a belated and trivial epilogue, though one so complex that we have not been able to unravel all its details. It seems that many of the older, less adventurous races refused to leave their homes; our di•rect ancestors were
among them. Most of these races fell into decadence and are now extinct, though some may still sur•vive. Our own world barely escaped the same fate. During the transition centuries-which actually lasted for millions of
years-the knowledge of the past was lost or else deliberate•ly destroyed. The latter, hard though it is to believe, seems more probable. For ages, man san into a superstitious yet still scientific barbarism during which he distorted history to remove his sense of impotence and failure. The legends of the invaders are completely false, although the desperate struggle against the mad mind undoubtedly contributed some•thing to them. Nothing drove our ancestors
back to earth except the sickness in their souls. "When we made this discovery, one problem in particular puzzled us in lys. The battle of shalmirane never occurred -yet shalmirane existed, and exists to this day.
What is more, it was one of the greatest weapons of destruction ever built. "It took us some time to resolve this puzzle, but the answer, once it was found, was very simple. Long ago our earth had a single giant satellite, the moon. When, in the tug of war between the tides and gravity, the moon at l began to fall, it became necessary to destroy it. Shalmirane was built for that purpose, and around its use were woven the legends you all know." callitrax smiled a little ruefully at his immense audience. "There are many such legends, partly true and partly false, and other paradoxes in our past which have not yet been resolved. That problem, though, is one for the psy•chologist rather than the historian. Even the records of the central computer cannot be wholly trusted, and bear clear evidence of tampering in th very remote past. "On earth, only diaspar and lys survived the period of decadence-diaspar thanks to the perfection of its machines, lys owing to its partial isolation and the unusual intellectual powers of its people. But both cultures, even when they had struggled back to their former level, were distorted by the fears and myths they had inherited. "These fears need haunt us no longer. It is not my duty as a historian to predict the future, only observe and interpretthe past. But its lesson is clear enough; we have lived too long out of contact with reality, and now the time has come to rebuild lives." Twenty-five Jeserac walked in silent wonder through the streets of

diaspar he had never seen. So different was it, indeed, from the city in wh he had passed all his lives that he would never have recognized it. Yet he knew that it was diaspar, though how he knew, he did not pause to ask. The streets were narrow, the buildings lower-and the park was gone. Or, rather, i did not yet exist. This was the diaspar before the change, the diaspar that had been open to the world and to the universe. The sky above the city was pale blue and flecked with raveled wisps of cloud, slowly twisting and turnin in the winds that blew across the face of this younger earth. Passing throug and beyond the clouds were more substan•tial voyagers of the sky. Miles above the city, lacing the heavens with their silent tracery, the ships that linked diaspar with the outer world came and went upon their business. Jeserac stare for a long time at the mystery and wonder of the open sky, and for a mome fear brushed against his soul. He felt naked and unprotected, conscious that this peace•ful, blue dome above his head was no more than the thinnest shells-that beyond it lay space, with all its mystery and menace. The fear w not strong enough to paralyze his will. In part of his mind jeserac knew th his whole experience was a dream, and a dream could not harm him. He would drift through it, savoring all that it brought to him, until he woke once m in the city that he knew. He was walking into the heart of diaspar, toward point where in his own age stood the tomb of yarlan zey. There was no tomb here, in this ancient city-only a low, circular building with many arched doorways leading into it. By one of those doorways a man was waiting for hi Jeserac should have been overcome with astonishment, but nothing could
surprise him now. Somehow it seemed right and natural that he should now be face to face with the man who had built diaspar. "You recognize me, i imagine," said yarlan zey. "Of course; i have seen your statue a thousand times. You are yarlan zey, and this is diaspar as it was a billion years a I know i am dreaming, and that neither of us is really here." "then you ne not be alarmed at anything that happens. So follow me, and remember that nothing can harm you, since whenever you wish you can wake up in diaspar-in your own age." obediently, jeserac followed yarlan zey into the building, his mind a receptive, uncritical sponge. Some memory, or echo of a memory, warned him of what was going to happen next, and he knew that once he would have shrunk from it in horror. Now, however, he felt no fear. Not only did he f protected by the knowledge that this experience was not real, but the presenc of yarlan zey seemed a talisman against any dangers that might confront him. There were few people drifting down the glideways that led into the depths o the building, and they had no other company when presently they stood in silence beside the long, streamlined cylinder which, jeserac knew, could carry him out of the city on a journey that would once have shat•tered his mind. When his guide pointed to the open door, he paused for no more than a mome on the threshold, and then was through. "You see?" said yarlan zey with a smile. "Now relax, and remember that you are safe-that nothing can touch you. jeserac believed him. He felt only the faintest tremor of apprehension as the tunnel entrance slid silently toward him, and the machine in which he was traveling began to gain speed as it hurtled through the depths of the earth. Whatever fears he might have had were forgotten in his eagerness to talk wit this almost mythical figure from the past. "Does it not seem strange to you, began yarlan zey, "that though the skies are open to us, we have tried to ourselves in the earth? It is the beginning of the sickness whose ending you have seen in your age. Humanity is trying to hide; it is frightened of what lies out there in space, and soon it will have closed all the doors that l into the uni•verse." "but i saw spaceships in the sky above diaspar," said jeserac. "You will not see them much longer. We have lost contact with the stars, and soon even the planets will be deserted. It took us millions of years to make the outward journey-but only centuries to come home again. And in a little while we will have abandoned almost all of earth itself." "why you do it?" asked jeserac. He knew the answer, yet somehow felt impelled to ask the question. "We needed a shelter to protect us from two fears-fear of death, and fear of space. We were a sick people, and wanted no further part

the universe so we pretended that it did not exist. We had seen chaos ragin through the stars, and yearned for peace and stability. Therefore diaspar had to be closed, so that nothing new could ever enter it. "We designed the cit that you know, and invented a false past to conceal our cowardice. Oh, we w not the first to do that-but we were the first to do it so thoroughly. And redesigned the human spirit, robbing it of ambition and the fiercer passions, so that it would be contented with the world it now possessed. "It took a thousand years to build the city and all its ma•chines. As each of us completed his task, his mind was washed clean of its memories, the carefully planned pattern of false ones was implanted, and his identity was stored in the city's circuits until the time came to call it forth again. "So at last there came a day when there was not a single man alive in diaspar; there w only the central computer, obeying the orders which we had fed into it, and controlling the memory banks in which we were sleeping. There was no one who had any contact with the past-and so at this point, history began. "Then, on by one, in a predetermined sequence, we were called out of the memory circui and given flesh again. Like a machine that had just been built and was now operating for the first time, diaspar began to carry out the duties for whic it had been designed." "yet some of us had had doubts even from the beginni Eternity was a long time; we recognized the risks involved in leaving no outlet, and trying to seal ourselves completely from the universe. We could
not defy the wishes of our cul•ture, so we worked in secret, making the modifications we thought necessary." "the uniques were our invention. They would appear at long intervals and would, if circumstances allowed them, dis•cover if there was anything beyond diaspar that was worth the effort of
contacting. We never imagined that it would take so long for one of them to succeed-nor did we imagine that his success would be so great." despite that suspension of the critical faculties which is the very essence of a dream, jeserac wondered fleetingly how yarlan zey could speak with such knowledge of things that had happened a billion years after his time. It was very con•fusing... He did not know where in time or space he was. The journey wa coming to an end; the walls of the tunnel no longer flashed past him at su breakneck speed. Yarlan zey began to speak with an urgency, and an authority, which he had not shown before. "The past is over; we did our work, for bet or for ill, and that is finished with. When you were created, jeserac, you were given that fear of the outer world, and that com•pulsion to stay within the city, that you share with everyone else in diaspar. You know now that t fear was ground•less, that it was artificially imposed on you. I, yarlan zey, who gave it to you, now release you from its bondage. Do you understand?" w those last words, the voice of yarlan zey became louder and louder, until it seemed to reverberate through all of space. The subterranean carrier in which he was speeding blurred and trembled around jeserac as if his dream was comi to an end. Yet as the vision faded, he could still hear that imperious voic thundering into his brain: "you are no longer afraid, jeserac. You are no longer afraid." he struggled up toward wakefulness, as a diver climbs from th ocean depths back to the surface of the sea. Yarlan zey had vanished, but there was a strange interregnum when voices which he knew but could not recognize talked to him encouragingly, and he felt himself supported by
friendly hands. Then like a swift dawn reality came flooding back. He opened his eyes, and saw alvin and hilvar and gerane standing anxiously beside him. But he paid no heed to them; his mind was too filled with the wonder that lay spread before him-the panorama of forests and rivers, and the blue vault of the open sky. He was in lys; and he was not afraid. No one disturbed h the timeless moment imprinted itself forever on his mind. At last, when he b satisfied him•self that this indeed was real, he turned to his companions. "Thank you, gerane," he said. "I never believed you would succeed." the psychologist, looking very pleased with himself, was making delicate
adjustments to a small machine that hung in the air beside him. "You gave u some anxious moments," he admitted. "Once or twice you started to ask
questions that couldn't be an•swered logically, and i was afraid i would have

to break the sequence." "suppose yarlan zey had not convinced me-what would
you have done then?" "we would have kept you unconscious, and taken you back to diaspar where you could have waked up naturally, without ever knowing that you'd been to lys." "and that image of yarlan zey you fed into my mind •ho much of what he said was the truth?" "most of it, i believe. I was much m anxious that my little saga should be convincing rather than historically ac•curate, but callitrax has examined it and can find no errors. It is certainly consistent with all that we know about yarlan zey and the origins diaspar." "so now we can really open the city," said alvin. "It may take a long time, but eventually we'll be able to neutralize this fear so that everyone who wishes can leave diaspar." "it will take a long time," replied gerane dryly. "And don't forget that lys is hardly large enough to hold several hundred million extra people, if all your people decide to come here. I don't think that's likely, but it's possible." "that problem will solve itself," answered alvin. "Lys may be tiny, but the world is wide. Why should we let the desert keep it all?" "so you are still dreaming, alvin," said jeserac with a smile. "I was wondering what there was left for you to do." alvin did not answer; that was a question which had be•come more and more insistent in his own mind during the past few weeks. He remained lost in thought, falling behind the others, as they walked down the hill toward
airlee. Would the centuries that lay ahead of him be one long anticlimax? Th answer lay in his own hands. He had discharged his destiny; now, perhaps, he could begin to live. Twenty-six There is a special sadness in achievement, in the knowl•edge that a long-desired goal has been attained at last, and th life must now be shaped toward new ends. Alvin knew that sadness as he wandered alone through the forests and fields of lys. Not even hilvar accompanied him, for there are times when a man must be apart even from his closest friends. He did not wander aimlessly, though he never knew which village would be his next port of call. He was seeking no particular place, but a mood, an influence-indeed a way of life. Diaspar had no need of him the ferments he had introduced into the city were working swiftly, and
noth•ing he could do would accelerate or retard the changes that were
happening there. This peaceful land would also change. Often he wondered if h had done wrong, in the ruthless drive to satisfy his own curiosity, by openi up the ancient way between the two cultures. Yet surely it was better that should know the truth-that it also, like diaspar, had been partly founded upo fears and falsehoods. Sometimes he wondered what shape the new society would take. Ire believed that diaspar must escape from the prison of the memory banks, and restore again the cycle of life and death. Hilvar, he knew, was sure that this could be done, though his proposals were too technical for alvin to follow. Perhaps the time would come again when love in diaspar was longer completely barren. Was this, alvin wondered, what he had always lacked in diaspar-what he had really been seeking? He knew now that when power and ambition and curiosity were satisfied, there still were left the longings of the heart. No one had really lived until they had achieved that synthesis of love and de•sire which he had never dreamed existed until he came to lys. H had walked upon the planet of the seven suns-the first man to do so in a billion years. Yet that meant little to him now; sometimes he thought he wou give all his achieve•ments if he could hear the cry of a newborn child, and know that it was his own. In lys, he might one day find what he wanted; t was a warmth and understanding about its.people, which, he now realized, was lacking in diaspar. But before he could rest, be•fore he could find peace, there was one decision yet to be made. Into his hands had come power; that power he still pos•sessed. It was a responsibility he had once sought and ac•cepted with eagerness, but now he knew that he could have no peace while was still his. Yet to throw it away would be the betrayal of a trust. He
in a village of tiny canals, at the edge of a wide lake, when he made his decision. The colored houses, which seemed to float at anchor upon the gentle waves, formed a scene of almost unreal beauty. There was life and warmth and comfort here-everything he had missed among the desolate grandeur of the seven

suns. One day humanity would once more be ready for space. What new chapter man would write among the stars,. Al•vin did not know. That would be no concern of his; his fu•ture lay here on earth. But he would make one more flight before he turned his back upon the stars. When alvin checked the upwa rush of the ascending ship, the city was too distant to be recognized as th work of man, and the curve of the planet was already visible. Presently they could see the line of twilight, thousands of miles away on its unending marc across the desert. Above and around were the stars, still brilliant for all the glory they had lost. Hilvar and jeserac were silent, guessing but not knowing with certainty why alvin was making this flight, and why he had aske them to come with him. Neither felt like speech, as the desolate panorama unfolded below them. Its emptiness oppressed them both, and jeserac felt a sudden contemptuous anger for the men of the past who had let earth's beauty die through their own neglect. He hoped that alvin was right in dreaming tha all this could be changed. The power and the knowledge still existed -it needed only the will to turn back the centuries and make the oceans roll again. The water was still there, deep down in the hidden places of the ear or if necessary, transmuta•tion plants could be built to make it. There was much to do in the years that lay ahead. Jes•erac knew that he stood between two ages; around him he could feel the pulse of mankind beginning to quicken again. There were great problems to be faced-but diaspar would face them. The recharting of the past would take centuries, but when it was finished man would have recovered almost all that he had lost. Yet could he regain it al Jeserac wondered. It was hard to believe that the galaxy would be reconquered and even if that were achieved, what purpose would it serve? Alvin broke int his reverie, and jeserac turned from the screen. "I wanted you to see this," said alvin quietly. "You may never have another chance." "you're not leaving earth?" "no; i want nothing more of space. Even if any other civ•ilizations still survive in this galaxy, i doubt if they will be worth the effort of finding. There is so much to do here; i know now that this is my home, an am not going to leave it again." he looked down at the great deserts, but eyes saw in•stead the waters that would be sweeping over them a thousand yea from now. Man had rediscovered his world, and he would make it beautiful whi he remained upon it. And after that- "we aren't ready to go out to the sta and it will be a long time before we can face their challenge again. I hav been wondering what i should do with this ship; if it stays here on earth, shall always be tempted to use it, and will never have any peace of mind.
i cannot waste it; i feel that it has been given into my trust, and i mus it for the benefit of the world. "So this is what i have decided to do. I going to send it out of the galaxy, with the robot in control, to discover what happened to our ancestors-and, if possible, what it was they left our universe to find. It must have been some•thing wonderful for them to have abandoned so much to go in search of it. "The robot will never tire, howeve long the journey takes. One day our cousins will receive my message, and they'll know that we are waiting for them here on earth. They will return,
i hope that by then we will be worthy of them, however great they have become." alvin fell silent, staring into a future he had shaped but which he might never see. While man was rebuilding his world, this ship would be crossing the darkness between the galaxies, and in thousands of years to come it would return. Perhaps he would still be here to meet it, but if not, he well content. "I think you are wise," said jeserac. Then, for the last time, the echo of an ancient fear rose up to plague him. "But suppose," he added, "the ship makes contact with something we do not wish to meet...." His voice faded away as he recognized the source of his anxiety and he gave a wry, self•deprecatory smile that banished the last ghost of the invad•ers. "You forget," said alvin, taking him more seriously than he expected, "that we wil soon have vanamonde to help us. We don't know what powers he possesses, but everyone in lys seems to think they are potentially unlimited. Isn't that so, hilvar?" hilvar did not reply at once. It was true that vanamonde was the other great enigma, the question mark that would always lie across the future

of humanity while it remained on earth. Already, it seemed certain, vanamonde's evolution toward self-consciousness had been accelerated by his contact with the philosophers of lys. They had great hopes of future
co-operation with the childlike supermind, believing that they could
foreshorten the aeons which his natural development would require. "I am not sure," confessed hilvar. "Somehow, i don't think that we should expect too
much from vanamonde. We can help him now, but we will be only a brief inci in his total life span. I don't think that his ultimate destiny has anything to do with ours." alvin looked at him in surprise. "Why do you feel that?" asked. "I can't explain it," said hilvar. "It's just an intuition." he could have added more, but he kept his silence. Thesematters were not capable of communication, and though alvin would not laugh at his dream, he did not car to discuss it even with his friend. It was more than a dream, he was sure that, and it would haunt him forever. Somehow it had leaked into his mind, during that indescribable and unsharable contact he had had with vanamonde.
Did vanamonde himself know what his lonely destiny must be? One day the energies of the black sun would fail and it would release its prisoner. And then, at the end of the uni•verse, as time itself was faltering to a stop, vanamonde and the mad mind must meet each other among the corpses of the stars. That conflict might ring down the curtain on creation it•self. Yet it was a conflict that had nothing to do with man, and whose outcome he would never know... "Look!" said alvin suddenly. "This is what i wanted to show yo Do you understand what it means?" the ship was now above the pole, and the planet beneath them was a perfect hemisphere. Looking down upon the belt of twilight, jeserac and hilvar could see at one instant both sunrise and sunset on opposite sides of the world. The sym•bolism was so perfect, and so striking, that they were to re•member this moment all their lives. In this universe the night was falling; the shadows were lengthening toward an east that would not know another dawn. But elsewhere the stars were still young a the light of morning lingered; and along the path he once had fol•lowed, man would one day go again. The End

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