"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…"

"The greatest good is the knowledge of truth."

"The will is by its nature so free that it can never be constrained."

"I confess that I have never found in my experience that anything which I once clearly understood could afterwards be called into doubt by me."

"I have never had any experience that was not accompanied by some thought."