Obviously, then, if in the first place the natural outlets of emotional excitement are bodily motions and vocal sounds, if in the second place the observation of such motions and sounds arouses the impulse to imitate them, and if finally this imitation produces again in the imitator the states of mind which first set the whole process going, then these motions and sounds, these inchoate germs of dance and song, possess an enormous latent power of expression, and need only to be systematized to become a wonderfully eloquent language. Such a language, in fact, is music.
At this point, however, it is important not to go too fast. These crude gestures and cries by which primeval man expressed his feelings, though they were the germs out of which music grew, were as yet no more music, which is not only expressive sound, but formed, articulate sound, than an infant's cooings are speech. So far they were mere ebullitions, purposeless and formless; before they could become communicative they must become definite, they must take on some organic structure. Now gestures, bodily movements, are very easily grouped together by means of accent. Every walker knows that it is difficult not to emphasize alternate steps, grouping the unaccented with the accented into a cluster of two. Every waltzer makes a similar grouping of three steps, one accented, the other two subordinate. Some such system of grouping is instinctively adopted whenever we have a series of impressions regularly recurring in time. Let the reader, listening to the ticking of a watch, note how impossible it is to attend to each tick by itself. He will inevitably group them in twos; the accent may come on the first or on the last of the group, but he cannot hear them as exactly equal, any more than in walking he can put exactly equal stress on each step. It was this tendency of the mind to group its impressions on a basis of equal time measurements and unequal accents that led at the dawn of musical history to meter or rhythm, which is as persistent in music as it is in poetry. Metrical form was the natural means of giving definition to bodily movements, and as soon as it was developed enough to produce regular, easily imitated steps out of the chaotic gestures of naïve feeling, Dance was born.