"The existence of God is as evident as that of a triangle."

"He who has a firm and stable mind will find that in all conditions of life he can be master of himself."

"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 first precept was never to accept anything for true which I did not clearly know to be such."

"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 …"