Since different kinds of music have different effects upon the habit of the soul, Aristotle next inquires what kinds are suitable for education. "We accept," he says, "the classification made by certain philosophers, who divide songs into ethical, practical, and enthusiastic, assigning to them the different harmonies respectively, and we affirm that music is to be employed, not for one useful purpose alone, but for several; _first_, for instruction; _second_, for purgation; and _third_, for cultured leisure, for relaxation, and for recreation. It is obvious that all harmonies ought to be employed, though not all in the same way. The most ethical (_i.e._ those that most affect the _ethos_ or habit of the soul) must be employed for instruction; the practical and enthusiastic for entertainments by professional performers. For those emotions which manifest themselves powerfully in some souls are potentially present in all, with a difference in degree merely, _e.g._, pity, fear, and also enthusiasm, a form of excitement by which certain persons are very liable to be possessed. If we watch the effects of the sacred songs, we shall see that those persons are restored to a normal condition under the influence of those that solemnize the soul, just as if they had undergone medical treatment and purgation. The same thing must happen to all persons predisposed to pity, fear, or emotion generally, as well as to others in so far as they allow themselves to come within the reach of any of these; for them all there must exist some form or another of purgation and relief accompanied with pleasure. In this way those 'purgative' songs afford a harmless pleasure, and it is for this reason that there ought to be a legal enactment to the effect that performers giving public concerts should employ such harmonies and such songs. The fact is, since there are two kinds of public, the one free and cultivated, the other rude and vulgar, composed of mechanics, laborers, and the like, there must be entertainments and exhibitions to afford pastime to the latter as well as the former. As the souls of these people are, so to speak, perverted from the normal habit, so also among the harmonies there are abnormities, and among songs there are the strained and discolored; and each individual derives pleasure from that which is germane to his nature. For this reason performers must be allowed to produce this kind of music, for the benefit of this portion of the public.