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taking each note of the octave scale in turn as the starting-point. The effect of the theory of keys was to reduce the old harmoniai to scales differentiated by species. Already before Aristoxenus the seven species of the enharmonic octave had been enumerated and labelled with names borrowed or adapted from traditional modal names: Mixolydian, Lydian, Phrygian, Dorian, Hypolydian, Hypophrygian, Locrian (or Hypodorian). The names were subsequently applied to the species of the diatonic octave too.100 Whether this nomenclature was used by practising musicians or only by theorists is uncertain. In any case, it applied to the note-series on view in a given piece of music, the octave that best corresponded to its ambitus. So if we find a piece of music that has a compass of just an octave, with the tone/ semitone sequence T S T T T S Tas is actually the case with the Seikilos epitaph (15)we could say that its scale is the Phrygian octave. The key in which the piece is notated is not Phrygian but Ionian. But the shape of the scale must be more significant than the notation. |
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Yet its significance remains slight until we identify the tonic note. Only when we determine how the pattern of tones and semitones relates to the tonic will we know something about the modality of the piece. In the case of the Seikilos epitaph it is easy to establish that the fourth degree of the scale is the tonic. So its scale pattern may be represented as d e f g a b c' d', with tonic g. We can say that it displays the D or Phrygian octave-species, but as regards mode, we must say that it is in the G mode, and be resigned to knowing no Greek label that will express this. By the G mode we mean the mode in which the successive scale degrees from the tonic upwards are T T S T . . . and downwards T S T T . . . |
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There is no fixed relationship between the octave-species shown by a scale and the mode as defined by the position of the tonic. For example, Mesomedes' two hymns to the Sun and to Nemesis (18, 19) have the compass of an octave and a ninth respectively, both in the C or Lydian species (if we take the lowest note as determinative), and both in fact notated in the Lydian key. But the Sun hymn has its |
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100 Cleon. Harm. pp. 197.7 ff., 199. 3, records both uses; the diatonic alone appears in Aristid. Quint. p. 15. 10ff., Gaud. Harm. p. 346. 6ff. It was not until the 9th c. that the eight church modes received Greek names, and then on a false principle; see Chailley, op. cit. 115-19, NG xii. 381f. The use of terms such as 'Dorian', 'Lydian', etc., in relation to Western music, as when the third movement of Beethoven's Quartet op. 132 is said to be in the Lydian mode, is based on the nomenclature of the church modes and in no way reflects the ancient usage. |
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