René Descartes (31 March 1596 – 11 February 1650), a natural philosopher and writer who spent most of his adult life in the Dutch Republic. He has been called the "Father of Modern Philosophy", and much subsequent Western philosophy is a response to his writings, which are studied closely to this day. Descartes's influence in mathematics is also apparent; the Cartesian coordinate system—allowing geometric shapes to be expressed in algebraic equations—was named after him. He is credited as the father of analytical geometry. Descartes was also one of the key figures in the Scientific Revolution. Descartes is perhaps best known for the philosophical statement "Cogito ergo sum" (English: I think, therefore I am; or I am thinking, therefore I exist or I do think, therefore I do exist).