He must be able to hear them [the counter arguments] from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form; he must feel the whole force of the difficulty which the true view of the subject has to encounter and dispose of; else he will never really possess himself of the portion of truth which meets and removes that difficulty.

Whatever crushes individuality is despotism.

Everyone who receives the protection of society owes a return for the benefit.

We have a right, also, in various ways, to act upon our unfavorable opinion of anyone, not to the oppression of his individuality, but in the exercise of ours.

When one's ideas are not challenged, one's ability to defend them weakens.

There is a limit to the legitimate interference of collective opinion with individual independence: and to find that limit, and maintain it against encroachment, is as indispensable to a good condition of human affairs, as protection against political despotism.

Not only the grounds of the opinion are forgotten in the absence of discussion, but too often the meaning of the opinion itself... Instead of a vivid conception and a living belief, there remain only a few phrases retained by rote; or, if any part, the shell and husk only of the meaning is retained, the finer essence being lost.