"I concluded that I was a substance whose whole essence or nature consists in thinking, and whose being does not depend on any place or any material thing."

"To be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it."

"The chief cause of human error is the confused nature of our perceptions."

"The greatest good is the knowledge of truth."

"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 …"