part, and of part and whole, - a relation which may fitly be designated by one word, reciprocity. Reciprocity, then, indicates a unitary principle with a twofold application, according to the terms of the relation, - the reciprocity between part and part, and the reciprocity between part and whole. In each application it is to be also observed that it possesses a double aspect. It means the necessity of, first, the integrity of the organ in the exercise of its own organic functions, and, second, its co-operation with the other organs and with the whole organism in the exercise of their several organic functions. The principle of reciprocity so ascertained and defined in the organism is capable of the most precise and exact application to the social body, which is itself an organism. In the new application, the individual takes the place of the organ, and the community at large takes the place of the organism as a whole. With this interchange of terms, we find a mutual dependence between the several individuals on the, one hand, and between each individual and the community at large on the other, and we find also the double aspect of the relation in the necessity of freedom to each individual in the performance of his own function, that is, in the free development of his own life, and in the necessity of co-operation by each individual with others in the performance of their functions, that is, in the free development of their lives. The perception, in a more or less crude form, that this reciprocity is a principle of the social order, is one of the oldest heritages of thought in the possession of our race. It dates back certainly as far as the well known fable of the belly and the members, as told in the ancient days of Rome, and the separate aspects of it have caused the difference between the egoistic and the altruistic schools of morals. One set of philosophers seized upon its selfish aspect in the necessity of individual freedom, and, making the individual's happiness the ultimate goal, became the egoistic school in all its manifold forms. Another seized upon its disinterested aspect in the necessity of co-operation among the members of society, and, making the community's happiness the ultimate goal, became the altruistic school in its equally manifold forms.
A principle of reciprocal dependence, however, is not enough by itself to constitute the basis of a rationally sufficient theory of morals. Taken by itself it is not in any sense a law, that is, a rule of action, because it imports neither a necessity nor an obliga-
