No simplicity of mind, no obscurity of station, can escape the universal duty of questioning all that we believe.

Our lives our guided by that general conception of the course of things which has been created by society for social purposes.

This sense of power is the highest and best of pleasures when the belief on which it is founded is a true belief, and has been fairly earned by investigation.

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.

Remember that [scientific thought] is the guide of action; that the truth which it arrives at is not that which we can ideally contemplate without error, but that which we may act upon without fear; and you cannot fail to see that scientific thought is not an accompaniment or condition of human progress, but human progress itself.

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

We may always depend on it that algebra, which cannot be translated into good English and sound common sense, is bad algebra.