"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, the kno…"

"I have always held that the two questions, God and the Soul, were the chief of those which ought to be demonstrated by the help of philosophy rather than of theology."

"The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge."

"I desire to live in peace and to continue the life I have begun, adopting as my motto 'to live well, one must live concealed'."

"Doubt is the origin of wisdom."