Irrationally held truths may be more harmful than reasoned errors.

Only one absolute certainty is possible to man, namely that at any given moment the feeling which he has exists.

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

Science ... warns me to be careful how I adopt a view which jumps with my preconceptions, and to require stronger evidence for such belief than for one to which I was previously hostile. My business is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations.

Thoughtfulness for others, generosity, modesty, and self-respect are the qualities which make a real gentleman or lady.

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

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

If a little knowledge is dangerous, where is the man who has so much as to be out of danger.