The original necessity for this distinctive human phenomenon lies very deep among the primal forces of social life. The relations required to develope individual organisms failed in the further development of the social organism of organization. Co-ordination requires first a common interest, and then the establishment of a common consciousness. It was for the common interest of the individual cells to obtain food easily, and this drew them into closer relation. That relation being established, their co-existence became a unit, an entity, a thing with a conscious life of its own. In the fullest development of the most elaborate organisms, this holds good. There must be a common interest to be served by all this co-ordinate activity; and there must be a common consciousness established, whereby to serve most easily the common interest. When the component cells in our tissues shrink and fail for lack of nutrition, when the several organs weary of inaction and fretfully demand their natural exercise, the man does not say, “My tissues need replenishment” or “My organs need exercise”: he says, “I am hungry.” And that “I,” the personal consciousness directing the smooth interaction of all its parts, goes to work to get food. Social evolution rests on this common interest. Individual men are profited by social relation; and, therefore, they enter into social relation. Such relation requires a common consciousness, through which the co-ordinate action may take place; and the whole course of social development is marked by the constant extension of this social consciousness and its necessary vehicles. Language is our largest common medium, and leads on into literature, which is but preserved speech. The brain of man is the social organ, the organ of communication. Through it flows the current of thought, whereby we are enabled to work together. By so much as our brains hold in common, we can understand each other; and, therefore, some degree of common education is essential to free social development.