Ren Descartes (1596-1650) was a French philosopher, mathematician, and writer, known as the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings. He is perhaps best known for the philosophical statement "Cogito ergo sum" (French: Je pense, donc je suis; English: I think, therefore I am), found in part IV of Discourse on Method.
Translated by Laurence J. LaFleur.