"For the purposes of instruction, as has been said, we must employ ethical songs and the corresponding harmonies. Such a harmony is the Doric, as has already been remarked. We must likewise admit any other species of music that may have approved itself to such persons as have devoted attention to philosophic discussion and musical education.... In respect to the Doric harmony, it is universally admitted to be, of all harmonies, the most sedate, expressive of the most manly character. Moreover, since our principle is, that the mean between extremes is desirable and ought to be pursued, and the Doric harmony holds this relation to other harmonies, it follows that Doric songs should be taught to young people in preference to any other. Two things, however, must be kept in view, the practicable and the befitting. I mean that we must discuss what is specially practicable for different people, as well as what is befitting. This, indeed, will depend upon the different periods of life. For example, it would not be easy for persons in the decline of life to sing the intense harmonies; for them nature suggests the languid kinds. For this reason those musicians are right who blame Socrates for having condemned the languid harmonies, as subjects of instruction, on the ground that they were intoxicating. (By this term he did not mean inebriating, in the sense that wine is inebriating,--for wine renders boisterous rather than anything else,--but languid.) The truth is, with an eye to the future, to old age, instruction ought to be given in harmonies and songs of this sort. Moreover, if there is any harmony suitable for youth, as tending to refine as well as to instruct, as is the case notably with the Lydian, it, of course, ought to be adopted. It is clear, then, that there are three distinct things to be considered in reference to education, avoidance of extremes, practicability, and appropriateness." So much for the four branches of study which, according to Aristotle, ought to compose the curriculum of youth. We have noticed that, in his extant works, he says little about Letters and Drawing. Just what branches the former was supposed to include, he has nowhere told us directly; but I think there can be little doubt that he gave a place to Grammar, Rhetoric (including Poetics), Dialectic, Arithmetic, Geometry, and Astronomy, which, along with Music, make up the Seven Liberal Arts, the _Trivium_ and _Quadrivium_ of the Middle Ages. This curriculum underwent considerable changes at different times, as we can see from Philo, Teles, Sextus Empiricus, St. Augustine, and others; but in Martianus Capella it returned to its original form, and in this dominated education for a thousand years. We might perhaps draw out Aristotle's programme of secondary education thus:--