The same use of harmonia is found in the Aristotelian Problems (xix. 26), where the question is asked, dia ti mesê kaleitai en tais harmoniais, tôn de oktô ouk esti meson, i.e. how can we speak of the Mesê or 'middle note' of a scale of eight notes?
We have now reviewed all the passages in Aristoxenus which can be thought to bear upon the question whether the harmoniai or Modes of early Greek music are the same as the tonoi or Keys discussed by Aristoxenus himself. The result seems to be that we have found nothing to set against the positive arguments for the identification already urged. It may be thought, perhaps, that the variety of senses ascribed to the word harmonia goes beyond what is probable. In itself however the word meant simply 'musical scale [24].' The Pythagorean use of it in the sense of 'octave scale,' and the very similar use in reference to diagrams which represented the division of that scale, were antiquated in the time of Aristoxenus. The sense of 'key' was doubtless limited in the first instance to the use in conjunction with the names Dorian, &c., which suggested a distinction of pitch. From the meaning 'Dorian scale' to 'Dorian key' is an easy step. Finally, in reference to genus harmonia meant the Enharmonic scale. It is not surprising that a word with so many meanings did not keep its place in technical language, but was replaced by unambiguous words, viz. tonos in one sense, systêma in another, genos enarmonion in a third. Naturally, too, the more precise terms would be first employed by technical writers.
§ 23. The Seven Species.
([See the Appendix, Table I.])
In the Harmonics of Aristoxenus an account of the seven species of the Octave followed the elaborate theory of Systems already referred to ([p. 48]), and doubtless exhibited the application of that general theory to the particular cases of the Fourth, Fifth, and Octave. Unfortunately the existing manuscripts have only preserved the first few lines of this chapter of the Aristoxenean work (p. 74, ll. 10-24 Meib.).
The next source from which we learn anything of this part of the subject is the pseudo-Euclidean Introductio Harmonica. The writer enumerates the species of the Fourth, the Fifth, and the Octave, first in the Enharmonic and then in the Diatonic genus. He shows that if we take Fourths on a Diatonic scale, beginning with Hypatê Hypatôn (our b), we get successively b c d e (a scale with the intervals ½ 1 1), c d e f (1 1 ½) and d e f g (1 ½ 1). Similarly on the Enharmonic scale we get—
| Hypatê Hypatôn to Hypatê Mesôn | b b* c e | (¼ ¼ 2 ) | ||
| Parhypatê " " Parhypatê " | b* c e e* | (¼ 2 ¼) | ||
| Lichanos " " Lichanos " | c e e* f | (2 ¼ ¼) |
In the case of the Octave the species is distinguished on the Enharmonic scale by the place of the tone which separates the tetrachords, the so-called Disjunctive Tone (tonos diazeuktikos). Thus in the octave from Hypatê Hypatôn to Paramesê (b-b) this tone (a-b) is the highest interval; in the next octave, from Parhypatê Hypatôn to Tritê Diezeugmenôn (c-c), it is the second highest; and so on. These octaves, or species of the Octave, the writer goes on to tell us, were anciently called by the same names as the seven oldest Keys, as follows: