To refuse a hearing to an opinion, because they are sure that it is false, is to assume that their certainty is the same thing as absolute certainty. All silencing of discussion is an assumption of infallibility.

So long as an opinion is strongly rooted in the feelings, it gains rather than loses in stability by having a preponderating weight of argument against it.

The general tendency of things throughout the world is to render mediocrity the ascendant power among mankind.

The test of real and vigorous thinking, the thinking which ascertains truths instead of dreaming dreams, is successful application to practice.

Over one's mind and over one's body the individual is sovereign.

We often hear the teachers of all creeds lamenting the difficulty of keeping up in the minds of believers a lively apprehension of the truth which they nominally recognize, so that it may penetrate the feelings, and acquire a real mastery over the conduct.... When it has come to be a hereditary creed, and to be received passively, not actively ... there is a progressive tendency to forget all of the belief except the formularies ... until it almost ceases to connect itself at all with the inner life of the human being.

Everything must be free to be written and published without restraint.