It seems strange that a character so unheroic should figure among the great emancipators of human thought. In fact, Descartes's services to liberty have been much exaggerated. His intellectual fame rests on three foundations. Of these the most indubitable is the creation of analytical geometry, the starting-point of modern mathematics. The value of his contributions to physics has been much disputed; but, on the whole, expert opinion seems to have decided that what was new in them was not true, and what was true was not new. However, the place we must assign Descartes in the history of philosophy can only be determined by our opinion of his metaphysics. {34} [Illustration: RENÉ DESCARTES.] {35} As a philosopher Descartes has, to begin with, the merit of exemplary clearness. The fault is not with him if we cannot tell what he thought and how he came to think it. The classic _Discourse on Method_ (1637) relates his mental history in a style of almost touching simplicity. It appears that from an early age truth had been his paramount object, not as with Bacon and Hobbes for its utility, but for its own sake. In search of this ideal he read widely, but without finding what he wanted. The great and famous works of literature might entertain or dazzle; they could not convince. The philosophers professed to teach truth; their endless disputes showed that they had not found it. Mathematics, on the other hand, presented a pleasing picture of demonstrated certainty, but a certainty that seemed to be prized only as a sure foundation for the mechanical arts. Wearily throwing his books aside, the young man then applied himself to the great book of life, mingling with all sorts and conditions of men to hear what they had to say about the prime interests of existence. But the same vanity and vexation of spirit followed him here. Men were no more agreed among themselves than were the authorities of his college days. The truths of religion seemed, indeed, to offer a safe refuge; but they were an exception that proved the rule; being, as Descartes observes, a supernatural revelation, not the natural knowledge that he wanted. The conflict of authorities had at least one good result, which was to discredit the very notion of {36} authority, thus throwing the inquirer back on his own reason as the sole remaining resource. And as mathematics seemed, so far, to be the only satisfactory science, the most reasonable course was to give a wider extension and application to the methods of algebra and geometry. Four fundamental rules were thus obtained: (1) To admit nothing as true that was not evidently so; (2) to analyse every problem into as many distinct questions as the nature of the subject required; (3) to ascend gradually from the simplest to the most complex subjects; and (4) to be sure that his enumerations and surveys were so exhaustive and complete as to let no essential element of the question escape.