As the note which is the meeting-point of the two tetrachords is doubtless the key-note, we shall not be wrong in making it the Mesê, and thus finding the octave in question in the Perfect System and in the oldest part of it, viz. the tetrachords Mesôn and Synêmmenôn, with the Nêtê Diezeugmenôn. How then did this octave come to be recognised by Lamprocles as distinctively Mixo-lydian? We cannot tell with certainty, because we do not know what the Mixo-lydian scale was before his treatment of it. Probably, however, the answer is to be sought in the relation in respect of pitch between the Dorian and Mixo-lydian keys. These, as we have seen ([p. 23]), were the keys chiefly employed in tragedy, and the Mixo-lydian was a Fourth higher than the other. Now when a scale consisting of white notes is transposed to a key a Fourth higher, it becomes a scale with one ♭. In ancient language, the tetrachord Synêmmenôn (a-b♭-c-d) takes the place of the tetrachord Diezeugmenôn. In some such way as this the octave of this form may have come to be associated in a special way with the use of the Mixo-lydian key.
However this may be, the change from the tetrachord Diezeugmenôn to the tetrachord Synêmmenôn, or the reverse, is a change of mode in the modern sense, for it is what the ancients classified as a change of System (metabolê kata systêma) [44]. Nor is it hard to determine the two 'modes' concerned, if we may trust to the authority of the Aristotelian Problems (l. c.) and regard the Mesê as always the key-note. For if a is kept as the key-note, the octave a-a with one ♭ is the so-called Dorian (e-e on the white notes). In this way we arrive at the somewhat confusing result that the ancient Dorian species (e-e but with a as key-note) yields the Hypo-dorian or modern Minor mode: while the Dorian mode of modern scientific theory [45] has its ancient prototype in the Mixo-lydian species, viz. the octave first brought to light by Lamprocles. The difficulty of course arises from the species of the Octave being classified according to their compass, without reference to the tonic character of the Mesê.
The Dorian mode is amply represented in the extant remains of Greek music. It is the mode of the two compositions of Dionysius, the Hymn to Calliope and the Hymn to Apollo ([p. 88]), perhaps also of Mr. Ramsay's musical inscription ([p. 90]). It would have been satisfactory if we could have found it in the much more important fragment of the Orestes. Such indications as that fragment presents seem to me to point to the Dorian mode (Mixo-lydian of Lamprocles).
3. The scales of the cithara furnish one example of the Phrygian species (d-d), and one of the Hypo-phrygian (g-g): but we have no means of determining which note of the scale is to be treated as the key-note.
In the Hymn to Nemesis, however, in spite of the incomplete form in which it has reached us, there is a sufficiently clear example of the Hypo-phrygian mode. It has been suggested as possible that the melody of Mr. Ramsay's inscription is also Hypo-phrygian, and if so the evidence for the mode would be carried back to the first century.
The Hypo-phrygian is the nearest approach made by any specimen of Greek music to the modern Major mode,—the Lydian or c-species not being found even among the scales of the cithara as given by Ptolemy. It is therefore of peculiar interest for musical history, and we look with eagerness for any indication which would allow us to connect it with the classical period of Greek art. One or two sayings of Aristotle have been thought to bear upon this issue.
The most interesting is a passage in the Politics (iv. 3, cp. p. 13), where Aristotle is speaking of the multiplicity of forms of government, and showing how a great number of varieties may nevertheless be brought under a few classes or types. He illustrates the point from the musical Modes, observing that all constitutions may be regarded as either oligarchical (government by a minority) or democratical (government by the majority), just as in the opinion of some musicians (hôs phasi tines) all modes are essentially either Dorian or Phrygian. What, then, is the basis of this grouping of certain modes together as Dorian, while the rest are Phrygian in character? According to Westphal it is a form of the opposition between the true Hellenic music, represented by Dorian, and the foreign music, the Phrygian and Lydian, with their varieties. Moreover, it is in his view virtually the same distinction as that which obtains in modern music between the Minor and the Major scales [46]. This account of the matter, however, is not supported by the context of the passage. Aristotle draws out the comparison between forms of government and musical modes in such a way as to make it plain that in the case of the modes the distinction was one of pitch (tas suntonôteras ... tas d' aneimenas kai malakas). The Dorian was the best, because the highest, of the lower keys,—the others being Hypo-dorian (in the earlier sense, immediately below Dorian), and Hypo-phrygian—while Phrygian was the first of the higher series which took in Lydian and Mixo-lydian. The division would be aided, or may even have been suggested, by the circumstance that it nearly coincided with the favourite contrast of Hellenic and 'barbarous' modes [47]. There is another passage, however, which can hardly be reconciled with a classification according to pitch alone. In the chapters dealing with the ethical character of music Aristotle dwells (as will be remembered) upon the exciting and orgiastic character of the Phrygian mode, and notices its especial fitness for the dithyramb. This fitness or affinity, he says, was so marked that a poet who tried to compose a dithyramb in another mode found himself passing unawares into the Phrygian (Pol. viii. 7). It is natural to understand this of the use of certain sequences of intervals, or of cadences, such as are characteristic of a 'mode' in the modern sense of the word, rather than of a change of key. If this is so we may venture the further hypothesis that the Phrygian music, in some at least of its forms, was distinguished not only by pitch, but also by the more or less conscious use of scales which differed in type from the scale of the Greek standard system.