The most important representative of this tendency was John Toland (1670-1720), who says, in his Christianity Not Mysterious (1696), that there is nothing in the Gospel which either transcends or conflicts with reason; but that priests and philosophers had transformed Christianity into a mystery. In his Pantheisticon (1720) he describes pantheism as the private theory of a society of enlightened gentlemen, who conceive God as the efficient energy of the universe. His most important book is the Letters to Serena (1704), in which he says, against the Cartesian and Spinozistic conception of nature, that motion is an attribute of matter which is equally primary with extension. Motion persists everywhere in nature, and all rest is only apparent.
2. Neither Locke nor the great systematizers of the seventeenth century had fully accepted the sublime ideal of knowledge proposed by Kepler and Galileo. They still regarded experience and reason as mutually exclusive. It was all the more significant therefore that Sir Isaac Newton (1642-1727), in his Principia Philosophiæ Naturalis Mathematica (1684), should furnish the most famous product of exact empirical science by means of a combination of induction and deduction. This work had a decisive influence on the further development of philosophy. But this is not the only ground for making reference to Newton in the history of philosophy. He is likewise the author of certain characteristic philosophic ideas.
Starting from the fact that weight is greater in the valley than on the mountain tops, and that all bodies which are tossed upward drop to the earth, Newton formulated the hypothesis that the heavenly bodies are also heavy and that they deviate from the direction implied by the
