"I can easily conceive that there is nothing in the world, that there is no heaven, no earth, no minds, no bodies; is it not then likewise true that I do not exist?"

"The perception of the understanding is sometimes obscure and confused, while that of the will is always clear and distinct."

"I confess that I have never been able to find out what is the 'substantial form' of a human body, or how it differs from the form of a statue."

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

"To know what is true is to know what is good."