Many a man will have the courage to die gallantly, but will not have the courage to say, or even to think, that the cause for which he is asked to die is an unworthy one.

Logic must no more admit a unicorn than zoology can.

The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken.

The desire to understand the world and the desire to reform it are the two great engines of progress, without which human society would stand still or retrogress.

There can't be a practical reason for believing something that is not true.

Only in thought is man a God; in action and desire we are the slaves of circumstance.

Through the greatness of the universe, which philosophy contemplates, the mind also is rendered great, and becomes capable of that union with the universe which constitutes its highest good.