"My purpose is not to teach a method which everyone ought to follow to guide his reason, but only to show how I have tried to guide mine."

"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…"

"I would not advise anyone to read my books who has not the leisure and inclination to meditate seriously with me."

"I am a thinking substance, that is, a mind, or soul, or intellect, or reason."

"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."