“Nothing is more dangerous than an idea when it is the only one you have.”

“As long as one remains curious, one makes progress; it is when you think you know everything that you are actually out of date.”

“When mores are sufficient, laws are unnecessary; when mores are insufficient, laws are unenforceable.”

“Leave your broom at the door...”

“Two things are aesthetically perfect in the world — the clock and the cat.”

“When men chose not to believe in God, they do not thereafter believe in nothing. They then become capable of believing in anything.”

“It has been said that, given two bettors, there is always one thief and one imbecile; that is true in certain cases when one of the two bettors is much better informed than the other, and knows it; but it can easily happen that two men of good faith, in complex matters where they possess exactly the same elements of information, arrive at different conclusions on the probabilities of an event, and that in betting together, each believes…that it is he who is the thief and the other the imbecile.”