"To allow opposition by speech seems to indicate that you think the speech impotent, as when a man says that he has squared the circle, or that you do not care whole-heartedly for the result, or that you doubt either your power or your premises. But when men have realized that time has upset many fighting faiths, they may come to believe even more than they believe the very foundations of their own conduct 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."

“Deep-seated preferences cannot be argued about — you cannot argue a man into liking a glass of beer — and therefore, when differences are sufficiently far reaching, we try to kill the other man rather than let him have his way. But that is perfectly consistent with admitting that, so far as appears, his grounds are just as good as ours.”

“Detached reflection cannot be demanded in the presence of an uplifted knife.”

“The power to tax is not the power to destroy while this Court sits.”

“When twenty years ago a vague terror went over the earth and the word socialism began to be heard, I thought and still think that fear was translated into doctrines that had no proper place in the Constitution or the common law. Judges are apt to be naif, simple-minded men, and they need something of Mephistopheles. We too need education in the obvious—to learn to transcend our own convictions and to leave room for much that we hold dear to be done away with short of revolution by the orderly change of law.”

“The general rule, at least, is that while property may be regulated to a certain extent, if regulation goes too far it will be recognized as a taking.”

“Holmes' Dissenting Opinion, Abrams vs. United States”