A man doesn't know what he knows until he knows what he doesn't know.

A censor is a man who knows more than he thinks you ought to.

A pessimist is a man who looks both ways when he crosses the street.

Ever since man invented the wheel, he has been the confused victim of the miracles he has wrought.

Expert: a man who makes three correct guesses consecutively.

A man convinced against his will is not convinced.