"Cogito, ergo sum" (Latin: "I think, therefore I am"), sometimes misquote as Dubito, ergo cogito, ergo sum (Latin: "I doubt, therefore I think, therefore I am"), is a philosophical statement used by René Descartes, which became a foundational element of Western philosophy. The simple meaning of the phrase is that if someone is wondering whether or not he exists, that is in and of itself proof that he does exist.