"The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, to the …"

"It is precisely because I am in the habit of using my senses to think of things that I find it difficult to think of anything else."

"The existence of God is a necessary consequence of my idea of God."

"Divide each difficulty into as many parts as is feasible and necessary to resolve it."

"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."