The chief doctrine maintained by Heraclides Ponticus is that there are three modes (harmoniai), belonging to the three Greek races—Dorian, Aeolian, Ionian. The Phrygian and Lydian, in his view, had no right to the name of mode or 'harmony' (oud' harmonian phÊsi dein kaleisthai tÊn Phrygion, kathaper oude tÊn Lydion). The three which he recognized had each a marked ethos. The Dorian reflected the military traditions and temper of Sparta. The Aeolian, which Heraclides identified with the Hypo-dorian of his own time, answered to the national character of the Thessalians, which was bold and gay, somewhat overweening and self-indulgent, but hospitable and chivalrous. Some said that it was called Hypo-dorian because it was below the Dorian on the aulos or flute; but Heraclides thinks that the name merely expressed likeness to the Dorian character (DÔrion men autÊn ou nomizein, prosempherÊ de pÔs ekeinÊ). The Ionian, again, was harsh and severe, expressive of the unkindly disposition fostered amid the pride and material welfare of Miletus. Heraclides is inclined to say that it was not properly a distinct musical scale or 'harmony,' but a strange aberration in the form of the musical scale (tropon de tina thaumaston schÊmatos harmonias). He goes on to protest against those who do not appreciate differences of kind (tas kat' eidos diaphoras), and are guided only by the high or low pitch of the notes (tÊ tÔn phthongÔn exytÊti kai barytÊti); so that they make a Hyper-mixolydian, and another again above that. 'I do not see,' he adds, 'that the Hyper-phrygian has a distinct ethos; and yet some say that they have discovered a new mode (harmonia), the Hypo-phrygian. But a mode ought to have a distinct moral or emotional character (eidos echein ethous hÊ pathous), as the Locrian, which was in use in the time of Simonides and Pindar, but went out of fashion again.' The Phrygian and Lydian, as we have seen, were said to have been brought to the Peloponnesus by the followers of Pelops.

The tone as well as the substance of this extract makes it evident that the opinions of Heraclides on questions of theoretical music must be accepted with considerable reserve. The notion that the Phrygian and Lydian scales were 'barbarous' and opposed to Hellenic ethos was apparently common enough, though largely due (as we may gather from several indications) to national prejudice. But no one, except Heraclides, goes so far as to deny them the name of harmonia. The threefold division into Dorian, Aeolian and Ionian must also be arbitrary. It is to be observed that Heraclides obtains his Aeolian by identifying the Aeolian of Pratinas and other early poets with the mode called Hypo-dorian in his own time. The circumstance that Plato mentions neither Aeolian nor Hypo-dorian suggests rather that Aeolian had gone out of use before Hypo-dorian came in. The conjecture of Boeckh that Ionian was the same as the later Hypo-phrygian (De Metr. Pind. iii. 8) is open to a similar objection. The Ionian mode was at least as old as Pratinas, whereas the Hypo-phrygian was a novelty in the time of Heraclides. The protest which Heraclides makes against classifying modes merely according to their pitch is chiefly valuable as proving that the modes were as a matter of fact usually classified from that point of view. It is far from proving that there was any other principle which Heraclides wished to adopt—such, for example, as difference in the intervals employed, or in their succession. His 'differences of kind' (tas kat' eidos diaphoras) are not necessarily to be explained from the technical use of eidos for the 'species' of the octave. What he complains of seems to be the multiplication of modes—Hyper-mixolydian, Hyper-phrygian, Hypo-phrygian—beyond the legitimate requirements of the art. The Mixo-lydian (e.g.) is high-pitched and plaintive: what more can the Hyper-mixolydian be? The Hypo-phrygian is a new mode: Heraclides denies it a distinctive ethos. His view seems to be that the number of modes should not be greater than the number of varieties in temper or emotion of which music is capable. But there is nothing to show that he did not regard pitch as the chief element, or one of the chief elements, of musical expression.

The absence of the name Hypo-lydian, taken with the description of Hypo-dorian as 'below the Dorian,' would indicate that the Hypo-dorian of Heraclides was not the later mode of that name, but was a semitone below the Dorian, in the place afterwards occupied by the Hypo-lydian. This is confirmed, as we shall see, by Aristoxenus (p. 18).