He began by doubting everything that could be doubted. Heir to the beliefs of all the ages, he determined to summon these, one by one, before the bar of reason, and force them to show cause for their existence. Everyone was to be called into court and put out that could be doubted. The existence of a God was called up and doubted, condemned, and put out. The existence of an external world was called up, doubted, condemned, and put out. In the same summary and shorthand way, man and mind were doubted and put out. All positive beliefs were doubted. After his process of elimination, he found himself without God, without man, without mind, without a permanent external world. All that remained after emptying himself of all mental furnishments and beliefs was the fact that he doubted. But he could not doubt without thinking. In the very act of doubting, he thought. If one thinks, he must think something. The nearest something to the thinking subject is his own personal being. So he thought himself and concluded, “I think, therefore, I am.” But he was not always; he began to be. So he must think of a being that caused him. The being that caused him must himself be uncaused. Moreover, there could not be an uncaused cause, without an effect. Creation, then, with which he stood face to face, was the effect of the great first cause. Thus Descartes’ method, based upon the thought underlying doubt, led him, necessarily, to himself, the object of his thought; and to God, the cause of himself; and to creation, the effect of the great first cause or God. Through his process of coming at the problem, he was able, rationally, to believe in the existence of himself, the outer world, and God, the cause of both. Descartes, as a thinker, was affirmative, positive, constructive. He only doubted down to the point where he could doubt no longer, that he might have a sure foundation upon which to build. His contribution gave fresh courage and inspiration to the human mind. He failed to determine the boundary line between the self and the not-self, between mind and matter, between the thinker and the creation with which he stood face to face. This was the work Spinoza proposed for himself, and in the celebrated Ethics, published to the world at the peril of his life and soul, imagined the task mathematically performed. The two poles of Descartes’ philosophy, the self and the not-self, he united in Descartes’ cause, and named the whole sum substance. The self and the not-self reappeared as attributes of substance, which Spinoza named thought and extension. All the phenomena in the universe, mental or material, were but modes of the infinite substance. The result of his thinking was pure pantheism. He reached a sort of mechanical unity, but he left no place for the affirmation of distinctions. His Ethics was large enough to accommodate everything, but in such a way as to preserve the individuality of nothing. A thought is valuable in proportion to its