René Descartes

René Descartes ( day-KART, also DAY-kart; French: [ʁəne dekaʁt] ; 31 March 1596 – 11 February 1650) was a French philosopher, mathematician, and scientist whose work was foundational to mathematics and modern philosophy, and influenced the development of early modern science. He connected the previously separate fields of geometry and algebra into analytic geometry, introduced a systematic method of inquiry that became influential in early modern philosophy, and made major contributions to epistemology and philosophy of mind as well as metaphysics.

Refusing to accept the authority of previous philosophers, Descartes frequently set his views apart from the philosophers who preceded him. In the opening section of the Passions of the Soul, an early modern treatise on emotions, Descartes goes so far as to assert that he will write on this topic "as if no one had written on these matters before". His best-known philosophical statement is "cogito, ergo sum" ("I think, therefore I am"; French: "Je pense, donc je suis").

His Meditations on First Philosophy and other philosophical works continue to be studied, and his legacy in mathematics is equally apparent. He credited as the father of analytic geometry, which facilitated the discovery of infinitesimal calculus and analysis, and the Cartesian coordinate system is named after him.