Descartes, Ren� 1596-1650
French philosopher and mathematician, usually regarded as the father of modern philosophy

Descartes was born near Tours in a small town now called La-Haye-Descartes, and was educated from 1604 to 1614 at the Jesuit College at La Fl�che. He remained a Catholic all his life, and he was careful to modify or even suppress some of his later scientific views, for example his sympathy with Nicolaus Copernicus, no doubt aware of Galilei's condemnation by the Inquisition in 1634. He studied law at Poitiers, graduating in 1616; then from 1618 he enlisted at his own expense for private military service, mainly in order to travel and to have the leisure to think. He was in Germany with the army of the Duke of Bavaria one winter's day in 1619 when he had his famous intellectual vision in the 'stove-heated room': he conceived a reconstruction of the whole of philosophy, and indeed of knowledge, into a unified system of certain truth modelled on mathematics and supported by a rigorous rationalism.

From 1618 to 1628 he travelled widely in Holland, Germany, France and Italy; then in 1628 returned to Holland where he remained, living quietly and writing until 1649. Few details are known of his personal life, but he did have an illegitimate daughter called Francine, whose death in 1640 at the age of five was apparently a terrible blow for him.

In 1649 he left Holland for Stockholm on the invitation of Queen Kristina who wanted him to give her tuition in philosophy. These lessons took place three times a week at 5am and were especially taxing for Descartes whose habit of a lifetime was to stay in bed meditating and reading until about 11am. He contracted pneumonia and died. His last words were supposedly a mon �me, il faut partir ('So my soul a time for parting'). He was buried in Stockholm but his body was later removed to Paris and eventually transferred to Saint-Germain-des-Pr�s.

Bibliography: Descartes' more popular works were published in French, the more scholarly ones first in Latin. The Discours de la m�thode (1637, 'Discourse on Method'), the Meditationes de prima Philosophia (1641, 'Mediations on First Philosophy') and the Principia Philosophiae (1644, 'Principles of Philosophy') set out the fundamental Cartesian doctrines: the method of systematic doubt; the first indubitably true proposition, je pense, donc je suis or cogito ergo sum ('I think, therefore I am'); the idea of God as the absolutely perfect Being; and the dualism of mind and matter.

Other philosophical works include Regulae ad directionem ingenii ('Rules for the Direction of the Mind', composed in the later 1620s, but unfinished and published posthumously in 1701) and Les Passions de l'�me (1649, 'Passions of the Soul'). He also made important contributions in astronomy, for example with his theory of vortices, and more especially in mathematics, where he reformed algebraic notation and helped to found co-ordinate geometry.

Bibliography: L J Beck, The Method of Descartes (1987); Leon Pearl, Descartes (1977); Elizabeth S Haldane, Descartes: His Life and Times (1905).