The Cartesian coordinate system is named after Rene Descartes. As a mathematician Descartes was credited with developing the system that still serves as the foundation for graphing some 350 years after his death. As a philosopher, he is famous for the phrase: “I think, therefore I am.” For more information on Descarte go to: http://www.maths.tcd.ie/pub/HistMath/People/Descartes/RouseBall/RB