In the act of song the same uniting force is present. To sing with another involves a contagious sympathy, in perhaps a higher degree than is the case with any other art. There is, in the first place, as in the dance, a unity of rhythm. Rhythm is based upon coöperation and, in turn, immensely strengthens the possibility of coöperation. In the bas-reliefs upon the Egyptian monuments representing the work of a large number of men who are moving a stone, we find the sculptured figure of a man who is beating the time for the combined efforts. Whether all rhythm has come from the necessities of common action or whether it has a physiological basis sufficient to account for the effect which rhythmic action produces, in any case when a company of people begin to work or dance or sing in rhythmic movement, their efficiency and their pleasure are immensely increased. In addition to the effect of rhythm we have also in the case of song the effect of unity of pitch and of melody, and the members of the tribe or clan, like those who to-day sing the Marseillaise or chant the great anthems of the church, feel in the strongest degree their mutual sympathy and support. For this reason, the Corroborees of the Australian, the sacred festivals of Israel, the Mysteries and public festivals of the Greeks, in short, among all peoples, the common gatherings of the tribe for patriotic or religious purposes, have been attended with dance and song. In many cases these carry the members on to a pitch of enthusiasm where they are ready to die for the common cause. Melodic and rhythmic sound is a unifying force simply by reason of form, and some of the simpler songs seem to have little else to commend them, but at very early periods there is not merely the song but the recital, in more or less rhythmic or literary form, of the history of the tribe and the deeds of the ancestors. This adds still another to the unifying forces of the dance and song. The kindred group, as they hear the recital, live over together the history of the group, thrill with pride at its glories, suffer at its defeats; every member feels that the clan's history is his history and the clan's blood his blood. § 4. FAMILY LIFE AS AN IDEALIZING AND SOCIALIZING AGENCY