Rene Descartes(Lat. Renatus .Cartesitts), a French philosopher, born at La Haye, Tou-raine, March 31, 1596, died in Stockholm, Feb. 11, 1650. He was the youngest son of a councillor of the parliament of Rennes, of an ancient and noble family, and early in life evinced such a disposition to inquire into the nature and causes of things, that he was called the young philosopher. His education was conducted in the Jesuit college of La Fleche, where he made rapid progress in the Greek and Latin classics, and the other ordinary studies of such an institution. He contracted also while there a friendship with Mersenne, which lasted until the end of his life; and though Mersenne became a monk, it was chiefly through him that Descartes communicated, from his profound scholastic retirement, with the outside learned world. After leaving college, in his 16th year, he occupied himself in preparing for the military life to which he was destined by the wishes of his family and the spirit of the times. But his health being delicate, he was sent to Paris with a tutor, to pass two years in the further prosecution of his studies.

In 1616 he joined the army of Maurice of Nassau, and while in garrison at Breda composed his Compendium Musicce, which seemed a prelude to the research for harmony which he was soon about to carry into all the realms of knowledge. He was driven to it, doubtless, by the painful uncertainty and chaotic confusion which reigned in nearly all the departments of human inquiry. He was troubled by the doubts of his epoch, but he shared also in its grand hopes. In 1619 he left the Dutch army, and entered as a volunteer the service of Maximilian of Bavaria, the head of the Catholic league; he was present at the battle of Praguo in 1620, and made with the imperialists the. campaign of Hungary in 1621. The atrocities which he witnessed in this war are said to have been the occasion of his resigning his commission. After visiting the greater part of the north of Europe, he returned to France, sold his estates, and speedily resumed his journeys. He spent some time in Switzerland and Italy, being present at Rome during the jubilee of 1625, and wherever he went observing the phenomena of nature, and perfecting himself in the acquisition of knowledge.

At Neuburg, on the Danube, where he passed the winter, the plan of devoting the remainder of his days to the reconstruction of the principles of human knowledge, which had long been maturing in his mind, took a definite shape. While he wandered from the Baltic to the Mediterranean, he was digesting the outlines of the great discoveries in geometry and method, destined soon to change the intellectual currents of the world. Going first to Paris, where he moved about from one obscure house to another to escape the intrusion of friends, he next settled in the neighboring country, and finally fixed his retreat in Holland. Emancipated from all social ties and relations, his life became that of an ascetic. In 1633 he made a brief visit to England, and the following, year to Amsterdam; and he constantly, through the mediation of Mersenne, maintained an active correspondence with the learned men who sought his instruction or his friendship. In 1637 he began a more open career by the publication of a volume entitled Discours de la methode, which contained treatises on method, on dioptrics, on meteors, and on geometry.

The first of these, besides an admirable picture of his life and of the progress of his studies, furnished a clear outline of a new science of metaphysics, only expanded in his later and larger works. In 1641 he published in Latin Meditationes de Prima Philosophia, which carried his speculations into abstruse questions as to the existence of God and the immortality of the soul. He invited criticisms of these, which in later editions are arranged and replied to under seven heads, wherein he considers all the objections raised to his original system. These works filled Europe with his name, and at the close of 1641 he was invited to France by Louis XIII., but he refused to quit his retirement. In 1644 appeared Principia Philosophic, which three years later was translated into French by Claude Picot. He then went to France, where a pension of 3,000 livres a year was conferred upon him; but as Queen Christina of Sweden invited him to Stockholm, at the same time appointing him director of an academy which she proposed to establish, at a salary of 3,000 crowns a year, he was induced once more to abandon his native country. The rigors of the climate, combined with the early hours exacted by the queen, in an eccentric wish to take lessons from him, led to his death in less than two years.

He was buried at Stockholm; but 16 years afterward Louis XIV. caused his remains to be disinterred and carried to France, where he was entombed in the church of Ste. Genevieve du Mont. - Descartes created an epoch in the history of the human mind, and should be classed with men like Plato, Aristotle, Bacon, Newton, and Kant. With Bacon, he was one of the founders of modern philosophy, but he pushed his inquiries further than Bacon in many respects, and in a somewhat different sphere. What the latter accomplished for natural science, Descartes accomplished for moral and metaphysical. As a metaphysician, he was the fountain head of the speculation of a whole subsequent century, while he added to his glory in that sphere the scarcely inferior distinction of a great discoverer in mathematics, and of an earnest laborer in nearly all the domains of physical science then known. Not wholly exempt from the errors of his day, he was yet immeasurably in advance of his day; while he enjoys this singular eminence among philosophers, that his expression is as clear and beautiful as his thought is great. French style appears nowhere more simple and direct than in the varied dissertations of Descartes, even when he treats of subjects the most recondite and difficult.

It was owing to this admirable clearness, perhaps, as much as to the more essential merits of his system, that it was said at the time of Descartes's death that everybody in England and France, who thought at all, thought Cartesianism. The fundamental principles of the philosophy of Descartes relate to his method, which takes its point of departure in universal doubt, and places the criterion of all certitude in evidence, or in other words, in reason, as the sovereign judge of the true and the false; to the erection of the individual consciousness into the fundamental ground and source of all correct philosophy (Cogito, ergo sum); to the radical distinction which is drawn between the soul and the body, the essential attribute of the former being thought, and that of the latter extension; to the demonstration of the existence of God from the very idea of the infinite; to the division of ideas into those which are innate, those which are factitious, or created by us, and those which are adventitious, or come from without by means of the senses; to the definition of substance, as that which so exists as to need nothing else for its existence, and which is applicable in the highest sense only to God, who has his ground in himself, but only relatively to the thinking and corporeal substances, which need the cooperation of God to their existence; and to the affirmation that the universe depends upon the productive power, not only for its first existence, but for its continued being and operation, or in other words, that conservation is perpetual creation.

Other points in this philosophy are important, and other aspects of it are to be regarded by the student; but for the popular reader these chiefly deserve attention, because these were characteristic and creative, and furnished the themes for the greater part of the agitated discussions of later years. From his theory of doubt, except upon evidence, for instance, the philosophy of the 17th century, and the whole of modern philosophy in fact, derived that disdain for the authority which formerly fettered the free movements of the mind, and that reliance upon reason, which Arnauld, Male-branche, Pascal, Bossuet, Fenelon, and others appealed to so effectively. The vivid determination of the consciousness, or the Me, as the proper object of metaphysical investigation, was the starting point of those great systems of thought, both Scotch and German, which are such remarkable phenomena in the history of intellectual development. It is also easy to trace to his doctrine of substance the pantheistic speculations of Spinoza, Fichte, and Hegel. In short, the schemes of Geulincx, Leibnitz, Wolf, Kant, and perhaps of Swedenborg, are all more or less directly affiliated to the great leading ideas of the French thinker.

As a whole, therefore, it is not surprising that his system produced an instant and vivid sensation. The scholastics were astonished by an assault at once so radical and so vital; the skeptics saw a skepticism more searching than theirs rising into the most solid religious faith; while the independent men of science, who had long been struggling against the methods of the old dialectics, received with joy a doctrine which seemed to place their researches on an immovable foundation, and to promise to crown them with the richest fruits of progress. For a while Descartes threatened to succeed to the place of absolute dictation and mastery which had been so long assigned to Aristotle. His influence passed from the cloister and the study to popular literature; all the great writers of the age of Louis XIV. were tinctured by it; but just as it appeared to have attained a universal acceptation, it began as rapidly to fade and shrink. The reasons of this decline are to be found partly in the growth of Locke's sensational philosophy; partly in the demonstrated impotence of Des-cartes's principles to resolve many of the higher problems to which he aspired; but chiefly in the discoveries of Newton and the progress of physics, which discredited his physical theories, and therefore brought his metaphysical conclusions into distrust.

The theory of vortices, by which he endeavored to explain the movements of the heavenly bodies, gave place to the simpler theory of Newton as to a law of universal gravitation; but science has not ceased to confess its obligations to Descartes for his important discoveries as to the application of algebra to geometry, his contributions to dioptrics, to mechanics, and to hydrostatics, and for that fearless spirit of investigation which, if it led him into mistakes, enabled him also to anticipate many truths ascribed to a later period. - After the death of Descartes, in addition to the works already mentioned, were published Le monde de Descartes, ou le traite de la lumiere (12mo, Paris, 1664); Le traite de l'homme et de la formation du foetus (4to, Paris, 1664); and Les lettres de Rene Descartes (3 vols. 4to, 1657-'67). The principal complete editions of his writings are: Opera Omnia (8 vols., Amsterdam, 1670-83); OEuvres completes de Descartes (9 vols., Paris, 1724); OEuvres completes de Descartes, by Victor Cousin (11 vols., 1824-'6), which is perhaps the most perfect edition; and OEuvres philosophiques de Descartes (1835), by Gar-nier, who added a life and a thorough analysis of all his writings.

The dissertations on his philosophy are almost without number, but the few most useful or curious are comprised in the following list: Recueil de pieces curi-euses concernant la philosophic de Descartes, published by Bayle (Amsterdam, 1684); Me-moires pour servir d l'histoire du Cartesia-nisme, by Huet (Paris, 1693); Memoires sur la persecution du Cartesianisme, by Cousin (Paris, 1838); Histoire et critique de la recolution cartesienne, by M. Francisque Bouillier (2 vols., Paris, 1842); and Le Cartesianisme, ou la veritable renovation des sciences, by Bor-dau-Demoulin (2 vols., Paris, 1843). Of late years the study of Descartes has revived among the French philosophers. See Damiron's Essat sur Vhistoire de la philosophic en France au XIXe siecle (1828) and Essai sur Vhistoire de la philosophic au XVI siecle (1846); Bouil-lier's Histoire de la philosophic cartesienne (2 vols., 1854; 2d ed., 1867); and Millet's Descartes, sa vie, etc. (1867).