PUBLISHERS' PREFACE. V 



child of the science that he vaunted, half child of the dead tradi- 

 tion that he detested ; for he had not stript himself entirely of the 

 past. That is possible for no man. 



Descartes stopped at Faith. His metaphysics was a rational- 

 ised theology, in which everything was merged in God, a theistic 

 monism. His psychology, his theory of the soul, were dualistic. -^ 

 Yet, despite their crudeness from the modern view, they were an 

 advance, and despite their author's seeming submissiveness to the 

 teachings of the Church, they were placed with his other doctrines 

 on the Index. The very search for a "criterion of truth" was 

 sufficient to condemn his system. 



But there was, in this action of the Church, a presage of the 

 disintegrating character of the new doctrines. Descartes' physics 

 practically nullified his theology, but he was careful not to give 

 offence. With the fate of Bruno, Campanella, and Galileo before 

 his eyes, he naturally felt, as a recent writer expresses it, "no 

 vocation for martyrdom." Nonetheless he pushed his mechanical- 

 ism to the extreme, and carried it to the very throne of his God, *C" 

 engulfing all nature and all life. With motion and extension alone, 

 supported by the laws of geometry, he constructed the Universe. 

 The construction was largely a priori and was in defiance of the 

 experimental principles that he so highly lauded, and in contra- 

 diction to the real mechanics that Galileo had just discovered and 

 which Descartes mistook, but it contained most of the theoretical 

 elements of the modern mechanical explanation of nature, and its 

 main hypotheses, as the theory of vortices, the uniform constitu- 

 tion of matter, etc., have persisted to this day. His ideas were, 

 thus, more powerful than even his own application of them, and 

 in the hands of his successors led to the undermining of the very 

 Faith which, from prudence or conviction, he himself had desired 

 to leave untouched. 



His system, even now, as shattered by modern research, and 

 in its ruins, with the towers of its real achievements projecting 

 aloft, presents a magnificent spectacle, daring in its scope and 

 execution. The defects of its construction are to be measured by 

 the standard of its time, not by the standard which through its 

 assistance succeeding centuries have been enabled to establish. If 

 it appears repellent in its aspect, harsh in its rigor, it must be re- 



