René Descartes remains to the Panthéon, he was reburied in the Abbey of Saint-Germain-des-Prés in 1819, missing a finger and skull. His skull is on display in the Musée de l'Homme in Paris. Initially, Descartes arrives at only a single first principle: I think. Thought cannot be separated from me, therefore, I exist ("Discourse on the Method" and "Principles of Philosophy"). Most famously, this is known as "cogito ergo sum" (English: "I think, therefore I am"). Therefore, Descartes concluded, if he doubted, then something or someone must be doing the doubting, therefore the very fact that he doubted proved his existence. "The
Descartes number Descartes number In number theory, a Descartes number is an odd number which would have been an odd perfect number, if one of its composite factors were prime. They are named after René Descartes who observed that the number would be an odd perfect number if only were a prime number, since the sum-of-divisors function for would satisfy, if 22021 were prime, where we ignore the fact that reveals that 22021 is composite. A Descartes number is defined as an odd number where and are coprime and , whence is taken as a 'spoof' prime. The example given is the