Some further notices of the harmoniai or modes are contained in the so-called Problems,—a collection which is probably not the work of Aristotle himself, but can hardly be later than the Aristotelian age. What is said in it of the modes is clearly of the period before the reform of Aristoxenus. In one place (Probl. xix. 48) the question is asked why the Hypo-dorian and Hypo-phrygian are not used in the chorus of tragedy. One answer is that the Hypo-phrygian has the ethos of action (Êthos echei praktikon), and that the Hypo-dorian is the expression of a lofty and unshaken character; both of these things being proper to the heroic personages on the stage, but not to the chorus, which represents the average spectator, and takes no part in the action. Hence the music suited to the chorus is that of emotion venting itself in passive complaint:—a description which fits the other modes, but least of all the exciting and orgiastic Hypo-phrygian. On the contrary (the writer adds) the passive attitude is especially expressed by the Mixo-lydian. The view here taken of the Hypo-dorian evidently agrees with that of Heraclides Ponticus (supra, p. 10).

The relation which Plato assumes between high pitch and the excitement of passion, and again between lowness of pitch and 'softness' or self-indulgence (malakia kai argia), is recognized in the Problems, xix. 49 epei de ho men barys phthongos malakos kai Êremaios estin, ho de oxys kinÊtikos, k.t.l.: 'since a deep note is soft and calm, and a high note is exciting, &c.'