Rene Descartes was one of the founders of modern thought, perhaps the most important intellectual figure of the 17th-century revolution that challenged Aristotelian systems of understanding. Descartes was raised by his maternal grandmother--his mother died shortly after giving birth to him--and was sent to the Jesuit School of La Fleche in Anjou at the age of 10. For nine years, he studied classical literature, history, rhetoric, philosophy, and theology, but questioned the worth of his learning. He spent several years in the military in Holland and Germany, obtained a law degree, and then embarked on a series of travels to seek knowledge within himself and in "the great book of the world." In 1619, inspired by his mathematician friend, Isaac Beeckman, Descartes founded a new scientific and philosophical method. He viewed math as the key to progress in the sciences, as well as the basis for all human understanding. He is responsible for the branch of mathematics known as coordinate or "Cartesian geometry." Descartes lived in Holland from 1629 to 1649. The following year, while in Sweden tutoring Queen Christina in philosophy, Descartes died of pneumonia. He is most famous for his simple rationalist credo: cogito ergo sum: "I think, therefore I am."