COGITO ERGO SUM
I THINK, THEREFORE I AM
He followed that famous quote with a logical argument claiming the existence of God. In essence, he argued that the idea of God, a perfect being, could only be caused by that perfect God. Fellow philosopher Pascal, an avid Christian, considered Descartes a mere deist. though he repeatedly wrote about his devotion to Roman Catholicism.
The Latinized version of his name is Renatus Cartesius, and to describe something with his qualities is to be Cartesian.