Poetry in general seems to have sprung from two causes, each of them lying deep in our nature. First, the instinct of imitation is implanted in man from childhood.... Next, there is the instinct for harmony and rhythm, metres being manifestly sections of rhythm. Persons, therefore, starting with this natural gift developed by degrees their special aptitudes, till their rude improvisations gave birth to Poetry. (ARISTOTLE: _Poetics_, iv. Butcher's translation, pp. 15, 17.) Poetry, music, and dancing constitute in Aristotle a group by themselves, their common element being imitation by means of rhythm--rhythm which admits of being applied to words, sounds, and the movements of the body. The history of these arts bears out the views we find expressed in Greek writers upon the theory of music; it is a witness to the primitive unity of music and poetry, and to the close alliance of the two with dancing.... The intimate fusion of the three arts afterward known as the "musical" arts--or rather we should perhaps say, the alliance of music and dancing under the supremacy of poetry--was exhibited even in the person of the artist. The office of the poet as teacher of the chorus demanded a practical knowledge of all that passed under the term "dancing," including steps, gestures, attitudes, and the varied resources of rhythmical movement.... The poet, lyric or dramatic, composed the accompaniment as well as wrote the verses; and it was made a reproach against Euripides, who was the first to deviate from the established usage, that he sought the aid of Iophon, son of Sophocles, in the musical setting of his dramas. The very word "poet" in classical times often implies the twofold character of poet and musician, and in later writers is sometimes used, like our "composer," in a strictly limited reference to music. Aristotle does full justice to the force of rhythmic form and movement in the arts of music and dancing. The instinctive love of melody and rhythm is, again, one of the two causes to which he traces the origin of poetry, but he lays little stress on this element in estimating the finished products of the poetic art. In the _Rhetoric_ he observes that if a sentence has metre it will be poetry; but this is said in a popular way. It was doubtless the received opinion, but it is one which he twice combats in the _Poetics_, insisting that it is not metrical form that makes a poem....