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

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.

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.

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

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

If a man, holding a belief which he was taught in childhood or persuaded of afterwards, keeps down and pushes away any doubts which arise about it in his mind, purposely avoids the reading of books and the company of men that call in question or discuss it, and regards as impious those questions which cannot easily be asked without disturbing it - the life of that man is one long sin against mankind.

Thought is powerless, except it make something outside of itself: the thought which conquers the world is not contemplative but active.