"The soul follows its own laws, and the body likewise follows its own laws; and they agree with each other in virtue of the pre-established harmony."

"The art of discovering the causes of phenomena, or true hypothesis, is like the art of deciphering, in which an ingenious conjecture often greatly shortens the road."

"Time is the order of successive phenomena."

"It is a great evil to be in doubt about the most important things."

"If you could blow the brain up to the size of a mill and walk about inside, you would not find consciousness."