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obscures it. After various efforts to accommodate the modal scales within the framework of one master scale, a system for doing so was worked out that gave general satisfaction. A fuller account of it will be given in Chapter 8. Here it must suffice to say that in place of an untidy collection of autonomous scales with individual features the student was invited to see a neat series of overlapping segments from the great scale. As this scale was transposed to a higher or lower pitch, different sections of it appeared within the compass of the voice or instrument. So according to this model it was key-changes that lay behind the variety of heard scales. A set of names for all the keys (tonoi) was devised, derived from names of the modes, and these key-names largely displaced the mode-names. It became difficult to speak of mode except in terms of key. But in being interpreted as a function of key, the modes were de-natured. They lost all idiosyncrasy. Only their scale-forms were considered; particularities such as differences of ambitus, emphasis on high or low notes, frequency of use, favoured intervals and melodic figures, and so forth, were ignored. |
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In musical practice, of course, the differences remained. In the musical texts and fragments from the Hellenistic and Roman periods we observe a variety of scales, predominantly diatonic, occasionally (in the earlier centuries) pentatonic or chromatic. These differences of genus are one form of modal difference, despite the ancient separation of the concepts. Apart from that, how are we to classify these scales, in particular the diatonic majority? |
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One might think that a clue would be given by the notation of different pieces in different keys. (The keys were each represented by a different selection from the repertory of note-symbols.) However, there is no necessary correlation between the actual modality of a piece of music, as it appears to us, and the key chosen for notating it. The choice of key depended much more on the pitch at which it would be convenient to perform the piece, and on the instrument to be used.98 |
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Another criterion that looks promising but turns out to be problematic is that of octave-species. The octave-species99 are the seven different series of tone and semitone intervals obtained by |
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98 According to Anon. Bellerm. 28 there were four particular keys used by citharodes, while auletes used seven and organists six. |
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99 'Species' is the conventional rendering of the Greek eidos, but 'aspect' would be better (Chailley, 99 n. 1). |
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