"The light of natural reason is sufficient to distinguish the true from the false."

"To be a good philosopher, one must be a good mathematician."

"To be able to live without fear, without anxiety, without sadness, and without any other passion which could disturb the tranquillity of the soul."

"I suppose therefore that all the things I see are false; I believe that none of those things ever existed which my fallacious memory represents to me; I consider that I possess no senses; I imagine th…"

"Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it."