"The will is by its nature so free that it can never be constrained."

"Travelling is almost like talking with those of other centuries."

"I resolved to feign that all the perceptions I had ever received were no truer than the illusions of my dreams."

"The mind is a substance whose whole essence or nature is to think, and which needs no place, nor depends on any material thing, in order to exist."

"It is not enough to possess a good mind; one must make good use of it."