"People are generally better persuaded by the reasons which they have themselves discovered than by those which have come into the mind of others."

"To ridicule philosophy is truly to philosophize."

"The last thing one discovers in writing a book is what to put first."

"How vain it is to boast of one's own merit, when one is but a fragment of the universe!"

"If we would purify the heart, we must purify the understanding."