"Beware of the books. It is not the book that is dangerous, but the spirit of the people who read it."

"The instruction we receive in our childhood is like the engraving on a stone, which time effaces but slowly."

"The public is a ferocious beast; one must chain it up or flee from it."

"Liberty of thought is the life of the soul."

"It is dangerous to be right in matters on which the established authorities are wrong."