The great end of life is not knowledge but action.

I have no faith, very little hope, and as much charity as I can afford.

Perhaps the most valuable result of all education is the ability to make yourself do the thing you have to do, when it ought to be done, whether you like it or not.

Irrationally held truths may be more harmful than reasoned errors.

Every great advance in natural knowledge has involved the absolute rejection of authority.

Agnosticism simply means that a man shall not say he knows or believes that for which he has no grounds for professing to believe.

Science comits suicide when it adopts a creed.

The deepest sin against the human mind is to believe things without evidence.