The historical figure famous for the quote "I think, therefore I am" is René Descartes, a French philosopher, mathematician, and scientist. This phrase, originally in Latin as "Cogito, ergo sum," is a foundational element of Western philosophy and emphasizes the importance of doubt and reason as the basis for knowledge. Descartes' work laid the groundwork for modern philosophy, and his method of systematic doubt encouraged questioning existing beliefs. His contributions to mathematics, such as Cartesian coordinates, also had a significant impact on the development of science and analytical geometry.