§ 8. The Aristotelian Problems.
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.'
§ 9. The Rhetoric.
The word tonos occurs several times in Aristotle with the sense of 'pitch,' but is not applied by him to the keys of music. The nearest approach to such a use may be found in a passage of the Rhetoric (iii. 1, p. 1403 b 27).
Speaking of the rise of acting (hypokrisis), which was originally the business of the poet himself, but had grown into a distinct art, capable of theoretical as well as practical treatment, he observes that a similar art might be formed for oratory. 'Such an art would lay down rules directing how to use the voice so as to suit each variety of feeling,—when it should be loud, when low, when intermediate;—and how to use the keys, when the pitch of the voice should be high or low or middle (kai pôs tois tonois, oion oxeia kai bareia kai mesê, sc. phônê); and the rhythms, which to use for each case. For there are three things which men study, viz. quantity (i. e. loudness of sound), tune, and rhythm (tria gar esti peri hôn skopousi, tauta d' esti megethos, harmonia, rhythmos).' The passage is interesting as showing the value which Aristotle set upon pitch as an element of effect. And the use of harmonia in reference to the pitch of the voice, and as virtually equivalent to tonos, is especially worthy of note.
§ 10. Aristoxenus.
Our next source of information is the technical writer Aristoxenus, a contemporary and pupil of Aristotle. Of his many works on the subject of music three books only have survived, bearing the title harmonika otoicheia [2]. In the treatment adopted by Aristoxenus the chapter on keys follows the chapter on 'systems' (systêmata). By a systêma he means a scale consisting of a certain succession of intervals: in other words, a series of notes whose relative pitch is determined. Such a system may vary in absolute pitch, and the tonoi or keys are simply the different degrees of pitch at which a particular system is taken (tous tonous eph' ôn tithemena ta systêmata melôdeitai). When the system and the key are both given it is evident that the whole series of notes is determined.