"The greatest good is to live without pain."

"The whole of philosophy is like a tree, whose roots are metaphysics, whose trunk is physics, and whose branches are all the other sciences."

"The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once."

"To be a good philosopher, one must be a good mathematician."

"It is not enough to apply our mind to things, but we must also apply it to ourselves."