René Descartes

René Descartes was born in 1596 at La Haye in Touraine, in the west of France, into a family of lawyers and officials. His mother died when he was an infant, and a delicate constitution earned him, at the Jesuit college of La Flèche, permission to stay in bed in the mornings — a habit of meditation he kept all his life. He studied law at Poitiers, then, wishing to read "the great book of the world", served as a gentleman volunteer in the armies of Maurice of Nassau and of the Duke of Bavaria. On the night of 10 November 1619, shut up in a stove-heated room in Germany, he had the series of dreams in which he believed he had glimpsed the foundations of a wonderful new science.

For nearly twenty years from 1628 he lived in the Dutch Republic, moving often and guarding his solitude, in correspondence with the learned men of Europe through his friend Marin Mersenne. There he wrote his treatise The World, which he withheld from publication when he learned of Galileo's condemnation in 1633. In 1637 he published, in French and without his name, the Discourse on Method together with three essays — the Dioptrics, the Meteors and the Geometry, the last of which founded analytic geometry. The Meditations on First Philosophy followed in 1641, the Principles of Philosophy in 1644 and The Passions of the Soul in 1649.

In 1649 Queen Christina of Sweden invited him to Stockholm to teach her philosophy. Obliged to attend her at five in the morning in the northern winter, he caught pneumonia and died there in February 1650. With his method of doubt, his "I think, therefore I am", his distinction between thinking substance and extended substance and his project of a mathematical science of nature, Descartes is counted the father of modern philosophy; every major thinker after him, from Spinoza and Leibniz to Kant and Hegel, began by measuring himself against his work.