We would not dare to conceive the things which are really mere commonplaces of existence.

Our fear of provoking religious hatred has rendered us unwilling to criticize ideas that are increasingly maladaptive and patently ridiculous.

We do not choose our concerns.

We must never make experiments to confirm our ideas, but simply to control them.

We ought not to desire the impossible.

Indiscriminate ideological suspicion of any idea, without the urge to exalt an idea of one's own, will discourage rather than promote lucidity.

We will not walk in fear, one of another. We will not be driven by fear into an age of unreason, if we dig deep in our own history and our doctrine and remember that we are not descended from fearful men. Not from men who feared to write, to speak, to associate, and to defend causes that were, for the moment, unpopular.... There is no way for a citizen of the Republic to abdicate his responsibility.

We do not ask ourselves what the ultimate ideas behind our civilization are that have brought us into this danger; we do not search for the human face behind the bewildering array of instruments that man has forged; in a word, we do not dare to be philosophical.

We will not walk in fear, one of another. We will not be driven by fear into an age of unreason, if we dig deep in our history and our doctrine; and remember that we are not descended from fearful men. Not from men who feared to write, to speak, to associate, and to defend causes that were for the moment unpopular.

An idea that is not dangerous is not worthy of being called an idea at all.

Don't join the book burners. Do not think you are going to conceal thoughts by concealing evidence that they ever existed.

We would not let ourselves be burned to death for our opinions: we are not sure enough of them for that.

Never take counsel of your fears.

We should forever forswear the masochistic process wherein we seek another's approval before we have even asked ourselves whether that person's views deserve to be listened to.