His quest for knowledge
“Cogito ergo sum” or “I think therefore I am” is Descartes's most famous quote that summarizes his quest for knowledge of ourselves and our world around us.[7] He gives a kind of proof of our own existence. He is thinking therefore he is existing. Although many of his scientific theories are dated and are now proved wrong he is still the source of a strong part of the Enlightenment, thinking and questioning.