It is indeed, in Rousseau's own thought, only one of the three different ways in which the basis of political union is stated, according to the preoccupation of his mind. When he is thinking quasi-historically, he describes his doctrine as that of the Social Contract.Modern anthropology, in its attempts to explain the complex by means of the simple, often strays further from the straight paths of history and reason. In a semi-legal aspect, using the terminology, if not the standpoint, of jurisprudence, he restates the same doctrine in the form of popular Sovereignty. This use tends continually to pass over into the more philosophical form which comes third. "Sovereignty is the exercise of the general will." Philosophically,Rousseau's doctrine finds its expression in the view that the State is based not on any original convention,not on, any determinate power, but on the living and sustaining rational will of its members. We have now to examine first Sovereignty and then the General Will,which is ultimately Rousseau's guiding conception.