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

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

"I have never made any discoveries that were not based on the certainty of mathematics."

"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."