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

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.

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

There is no scientific discoverer, no poet, no painter, no musician, who will not tell you that he found ready made his discovery or poem or picture — that it came to him from outside, and that he did not consciously create it from within.

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

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.

If I steal money from any person, there may be no harm done from the mere transfer of possession; he may not feel the loss, or it may prevent him from using the money badly. But I cannot help doing this great wrong towards Man, that I make myself dishonest.