This is the skeleton upon which Descartes constructs his theory. Even this cursory examination of it shows the obvious attempt to explain “the world of grace” by the method of mathematics, and it is quite consistent with the spirit of the Renaissance. The existence of God and the existence of matter are deduced in turn from the axiom of all thought, the Self; while matter is further described as the extended or the measurable. Thus Descartes has tried to construct a bridge between the scholastic concepts and the science of the Renaissance. The three realities, the Self, God, and matter, which Descartes often speaks of as intuitively certain, have obviously a differing cogency. The reality of consciousness is the ground from which the other two are derived. In asserting its primacy, he is voicing the spirit of the Renaissance even more clearly than did Galileo and Bacon. For Descartes in this has gone back of the objective facts to a single subjective principle; whereas the deductive principles of Galileo were objective. In this respect Descartes is the founder of the subjective method of modern thought, and in identifying the Self as the reason he became the founder of rationalism. In any case he established a background for epistemology, or the theory of knowledge. But in his derivation of the other two realities――God and matter――he shows how persistent was the scholastic current in his thought. Although he declared them to be intuitively known, they evidently are not so in the same sense that self-consciousness is; and he felt obliged to support them by traditional scholastic arguments. =God and the World.= Leaving these fundamental principles of Descartes, we now come to a consideration of a few of the details of his philosophy. Descartes’ world is a dualism in which conscious being stands in contrast with space objects. God is related to the world of mind on the one hand and to the world of matter on the other. The order in which Descartes came upon the three substances――the Self, God, and matter――is, however, not the order of their reality. In reality God is the _primary substance_, for He depends only upon Himself. Matter and the Self are _relative or created substances_, for they depend upon God. Matter and mind have different modes of appearing: the modes of matter are form, size, position, and motion. The modes of mind are ideas, judgments, and will. Thus mind is so essentially different from matter, as can be seen in their respective modes, that God stands in a different relation to each.