or Cartesius ( – ) and "And it is a mark of prudence never to trust wholly in those things which have once deceived us." "Je pense, donc je suis." Translation: "I think, therefore I am." Source: Discours de la méthode "Cogito, ergo sum." Translation: "I think, therefore I am." Source: Principia philosophiae "Ex nihilo nihil fit." Translation: "Nothing comes out of nothing." Source: Principia philosophiae "Dubium sapientiae initium." Translation: "Doubt is the origin of wisdom." Source: Meditationes de prima philosophiae See: list of people by name