Not to be absolutely certain is, I think, one of the essential things in rationality.

My own belief is that in most ages and in most places obscure psychological forces led men to adopt systems involving quite unnecessary cruelty, and that this is still the case among the most civilized races at the present day.

a generation that cannot endure boredom will be a generation of little men, of men unduly divorced from the slow process of nature, of men in whom every vital impulse slowly withers as though they were cut flowers in a vase.

It is because modern education is so seldom inspired by a great hope that it so seldom achieves great results.

There lies before us, if we choose, continual progress in happiness, knowledge and wisdom. Shall we instead choose death, because we cannot forget our quarrels? I appeal as a human being to human beings; remember your humanity, and forget the rest.

The very best proof that something can be done is that someone has already done it.

In action, in desire, we must submit perpetually to the tyranny of outside forces; but in thought, in aspiration, we are free, free from our fellowmen, free from the petty planet on which our bodies impotently crawl, free even, while we live, from the tyranny of death.