When men have realized that time has upset many fighting faiths, they may come to believe... that the ultimate good desired is better reached by free trade in ideas-- that the best test of truth is the power of the thought to get itself accepted in the competition of the market, and that truth is the only ground upon which their wishes safely can be carried out. That at any rate is the theory of our Constitution. It is an experiment. As all life is an experiment. Every year if not every day we wager our salvation upon some prophecy based upon imperfect knowledge.

Speak clearly, if you speak at all; carve every word before you let it fall.

Do not be bullied out of your common sense by the specialist; two to one, he is a pedant.

Science is the topography of ignorance.

I hate facts. I always say the chief end of man is to form general propositions - adding that no general proposition is worth a damn.

The sound of a kiss is not so loud as that of a cannon, but its echo lasts a great deal longer.

I think that, as life is action and passion, it is required of a man that he should share the passion and action of his time at peril of being judged not to have lived.