The danger to society is not merely that it should believe wrong things, though that is great enough; but that it should become credulous, and lose the habit of testing things and inquiring into them; for then it must sink back into savagery.

scientific thought does not mean thought about scientific subjects with long names. There are no scientific subjects. The subject of science is the human universe; that is to say, everything that is, or has been, or may be related to man.

There is one thing in the world more wicked than the desire to command, and that is the will to obey.

He who truly believes that which prompts him to an action has looked upon the action to lust after it, he has committed it already in his heart.

Namely, we have no right to believe a thing true because everybody says so unless there are good grounds for believing that some one person at least has the means of knowing what is true, and is speaking the truth so far as he knows it.

The scientific discovery appears first as the hypothesis of an analogy; and science tends to become independent of the hypothesis.

We feel much happier and more secure when we think we know precisely what to do, no matter what happens, then when we have lost our way and do not know where to turn.