Do not think of knocking out another person's brains because he differs in opinion from you. It would be as rational to knock yourself on the head because you differ from yourself ten years ago.

Silence is one of the hardest arguments to refute.

Never argue with stupid people, they will drag you down to their level and then beat you with experience.

Let no man pull you so low as to hate him.

We can never be sure that the opinion we are endeavoring to stifle is a false opinion; and if we were sure, stifling it would be an evil still.

The free flow of conflicting ideas and feelings is critical for creative thinking, for discovering new solutions no one individual would have come to on his own.

Give me the liberty to know, to utter, and to argue freely according to conscience, above all liberties.