A cat is witty, he has nerve, he knows how to do precisely the right thing at the right moment.
Mathematics is the art of giving the same name to different things.
Logic sometimes makes monsters. For half a century we have seen a mass of bizarre functions which appear to be forced to resemble as little as possible honest functions which serve some purpose.
A small error in the former will produce an enormous error in the latter.
One geometry cannot be more true than another; it can only be more convenient.
Most striking at first is the appearance of sudden illumination, a manifest sign of long unconscious prior work.