From Plato and Aristotle we have learned some elements of what may be called the gamut of sensibility. Between the higher keys which in Greece, as in Oriental countries generally, were the familiar vehicle of passion, especially of the passion of grief, and the lower keys which were regarded, by Plato at least, as the natural language of ease and license, there were keys expressive of calm and balanced states of mind, free from the violent extremes of pain and pleasure. In some later writers on music we find this classification reduced to a more regular form, and clothed in technical language. We find also, what is still more to our purpose, an attempt to define more precisely the musical forms which answered to the several states of temper or emotion.

Among the writers in question the most instructive is Aristides Quintilianus. He discusses the subject of musical ethos under the first of the usual seven heads, that which deals with sounds or notes (peri phthongÔn). Among the distinctions to be drawn in regard to notes he reckons that of ethos: the ethos of notes, he says, is different as they are higher or lower, and also as they are in the place of a ParhypatÊ or in the place of a Lichanos (p. 13 Meib. hetera gar ÊthÊ tois oxyterois, hetera tois baryterois epitrechei, kai hetera men parypatoeidesin, hetera de lichanoeidesin). Again, under the seventh head, that of melopoiia or composition, he treats of the 'regions of the voice' (topoi tÊs phÔnÊs). There are three kinds of composition, he tells us (p. 28), viz. that which is akin to HypatÊ (hypatoeidÊs), that which is akin to MesÊ (mesoeidÊs), and that which is akin to NÊtÊ (nÊtoeidÊs). The first part of the art of composition is the choice (lÊpsis) which the musician is able to make of the region of the voice to be employed (lÊpsis men di' hÊs heuriskein tÔ mousikÔ perigignetai apo poiou tÊs phÔnÊs to systÊma topou poiÊteon, poteron hypatoeidous Ê tÔn loipÔn tinos). He then proceeds to connect these regions, or different parts of the musical scale, with different branches of lyrical poetry. 'There are three styles of musical composition (tropoi tÊs melopoiias), viz. the Nomic, the Dithyrambic, and the Tragic; and of these the Nomic is netoid, the Dithyrambic is mesoid, and the Tragic is hypatoid.... They are called styles (tropoi) because according to the melody adopted they express the ethos of the mind. Thus it happens that composition (melopoiia) may differ in genus, as Enharmonic, Chromatic: in System, as Hypatoid, Mesoid, Netoid: in key, as Dorian, Phrygian: in style, as Nomic, Dithyrambic: in ethos, as we call one kind of composition "contracting" (systaltikÊ), viz. that by which we move painful feelings; another "expanding" (diastaltikÊ), that by which we arouse the spirit (thymos); and another "middle" (mesÊ), that by which we bring round the soul to calmness.'

This passage does not quite explicitly connect the three kinds of ethos—the diastaltic, the systaltic, the intermediate—with the three regions of the voice; but the connexion was evidently implied, and is laid down in express terms in the pseudo-Euclidean Introductio (p. 21 Meib.). According to this Aristoxenean writer, 'the diastaltic ethos of musical composition is that which expresses grandeur and manly elevation of soul (megaloprepeia kai diarma psychÊs andrÔdes), and heroic actions; and these are employed by tragedy and all poetry that approaches the tragic type. The systaltic ethos is that by which the soul is brought down into a humble and unmanly frame; and such a disposition will be fitting for amatory effusions and dirges and lamentations and the like. And the hesychastic or tranquilly disposed ethos (hÊsychastikon Êthos) of musical composition is that which is followed by calmness of soul and a liberal and peaceful disposition: and this temper will fit hymns, paeans, laudations, didactic poetry and the like.' It appears then that difference in the 'place' (topos) of the notes employed in a composition—difference, that is to say, of pitch—was the element which chiefly determined its ethos, and (by consequence) which distinguished the music appropriate to the several kinds of lyrical poetry.

A slightly different version of this piece of theory is preserved in the anonymous treatise edited by Bellermann (§§ 63, 64), where the 'regions of the voice' are said to be four in number, viz. the three already mentioned, and a fourth which takes its name from the tetrachord HyperbolaiÔn (topos hyperboloeidÊs). In the same passage the boundaries of the several regions are laid down by reference to the keys. 'The lowest or hypatoid region reaches from the Hypo-dorian HypatÊ MesÔn to the Dorian MesÊ; the intermediate or mesoid region from the Phrygian HypatÊ MesÔn to the Lydian MesÊ; the netoid region from the Lydian MesÊ to the NÊtÊ SynemmenÔn; the hyperboloid region embracing all above the last point.' The text of this passage is uncertain; but the general character of the topoi or regions of the voice is clearly enough indicated.

The three regions are mentioned in the catechism of Bacchius (p. 11 Meib.): topous (MSS. tropous) de tÊs phÔnÊs posous legomen einai? treis. tinas? toutous; oxyn, meson, baryn. The varieties of ethos also appear (p. 14 Meib.): hÊ de metabolÊ kata Êthos? hotan ek tapeinou eis megaloprepes; Ê ex hÊsychou kai synnou eis parakekinÊkos. 'What is change of ethos? when a change is made from the humble to the magnificent; or from the tranquil and sober to violent emotion.'

When we compare the doctrine of musical ethos as we find it in these later writers with the indications to be gathered from Plato and Aristotle, the chief difference appears to be that we no longer hear of the ethos of particular modes, but only of that of three or (at the most) four portions of the scale. The principle of the division, it is evident, is simply difference of pitch. But if that was the basis of the ethical effect of music in later times, the circumstance goes far to confirm us in the conclusion that it was the pitch of the music, rather than any difference in the succession of the intervals, that principally determined the ethical character of the older modes.