I do not propose to develop here the tortured processes of reasoning by which the rationalists were wont to convince themselves that _what_ God is and _that_ He is, were no mere questions of experience. It seemed to them as though the very meaning of God assured his existence. But I question if in the end any of our day would be strongly convinced by their argument about it. The whole matter is of the less importance that Spinoza’s results in the domain of ethics are not so dependent on his method but that one may readily reword the problem of 17th century rationalism in the language of modern science. Nevertheless it is in the first instance devotion to the method he had received from Descartes that requires Spinoza to differ with his master on two points of the greatest importance to the sequel. This God, this “all-perfect being” as the rationalists commonly defined Him, plays a rather capricious part in Descartes’ thinking. He is represented as the Creator of the physical universe, and in this act of creation as quite arbitrarily choosing this sort of a world rather than another, a world working out a destiny that is not chosen because it is good but is good because it is chosen of _God_. For the rest, what this end may be is beyond the ken of human reason, and after having done homage to the divine purpose Descartes feels at liberty to confine his attention to studying the mechanism and reconstructing the history of nature as we find it. Here one can imagine Spinoza exclaiming “What! You would follow the guidance of the geometers, deducing all truth from the axiom of God’s existence, and you leave it to God to decide what shall and what shall not follow from his nature!” Do then the axioms of geometry select the theorems they shall establish, accepting some and rejecting others for a motive whether good or bad? No, says Spinoza, God has neither intellect nor will: facts and laws follow from His nature as the properties of a triangle from its definition. The other element of caprice in Descartes’ final picture of the world is just _man_. He alone of all things occupying a place in God’s universe is not subjected to mechanical law. But how, Spinoza may well ask, can we conceive ourselves to be following the lead of mathematicians if we violate the first principles of their science? Does the geometry of a triangle depend upon the place in which the triangle finds itself? How then can the laws of the behavior of bodies depend upon these bodies being in or out of the human machine? The human body must be determined by the same laws of physics that govern all extended things. “And as for the mind,” Spinoza adds, “the order and connection of its ideas are parallel to the order and connection of the bodily states.” “There is,” he concludes, “in mind no absolute or free will; but the mind is determined to this or that volition by a cause which has itself been determined by another cause, this again by another and so on _in infinitum_.”