Descartes (da'-kart'), Rene. A great French philosopher and mathematician. Was born in Touraine in 1596. Descartes early adopted the profession of arms, and served in the armies of the Dutch and Bavarians. In 1629 he settled in Holland, in which country he devoted himself to his favorite studies of the natural and exact sciences. In 1637 Descartes produced his celebrated discourse on the "Method of Reasoning, and of Investigating Scientific Truth," and in 1641 he published his "Metationes de Prima Philosophia," a work of the grandest metaphysical research and speculation, indoctrinating a new system of philosophy named for its author, "Cartesianism." In 1644 Descartes' theory of the world appeared in the "Principia Philosophiae." Died 1650.

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