More quotes by René Descartes

"To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them."
"Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it."
"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."
"But in my opinion, all things in nature occur mathematically."
"I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me. I think I have no senses. I believe that body, shape, extension, motion, location are functions. What is there then that can be taken as true? Perhaps only this one thing, that nothing at all is certain."