Discourse on the Method

In this short, personal book of 1637, Descartes tells how he decided to doubt everything he had been taught and rebuild knowledge on certain foundations. He gives four simple rules of method and arrives at the one thing he cannot doubt: 'I think, therefore I am.' From there he goes on to God, the body as a machine and the future of science.

Written in French rather than Latin so that ordinary readers could follow it, the Discourse was originally the preface to three scientific essays, including the one that introduced coordinate geometry. Readers have often compared its journey through doubt with the autobiography of al-Ghazali five centuries earlier.

René Descartes (1596–1650) was educated by the Jesuits, served as a gentleman soldier, and on a winter night in 1619, shut in a stove-heated room in Germany, had the series of dreams that convinced him to rebuild all knowledge from scratch. He spent most of his adult life in the Netherlands, where he could work in peace.

His Discourse on the Method and Meditations made 'I think, therefore I am' the starting point of modern philosophy, and his invention of coordinate geometry joined algebra and geometry for good. Invited to Stockholm by Queen Christina, who wanted lessons at five in the morning, he caught pneumonia and died there in the winter of 1650.