"I have been nourished by books, and I have found in them a great deal of good as well as a great deal of evil."

"I suppose therefore that all I see is false. I believe that none of what my deceptive memory represents to me ever existed."

"I entirely abandoned the study of letters, resolving to seek no other science than that which could be found in myself, or at least in the great book of the world."

"I have long ago observed that in order to study the truth, it is necessary once in the course of our life to demolish everything completely and start again from the foundations."

"I concluded that I was a substance whose whole essence or nature consists only in thinking, and that, in order to exist, it needs no place and depends on no material thing."