There is only one inborn error. and that is the notion that we exist in order to be happy.

If the world were a paradise of luxury and ease, a land flowing with milk and honey, where every Jack obtained his Jill at once and without any difficulty, men would either die of boredom or hang themselves; or there would be wars, massacres, and murders; so that in the end mankind would inflict more suffering on itself than it has now to accept at the hands of Nature.

Any foolish boy can stamp on a beetle, but all the professors in the world cannot make a beetle.

If a person is stupid, we excuse him by saying that he cannot help it; but if we attempted to excuse in precisely the same way the person who is bad, we should be laughed at.

Physics is unable to stand on its own feet, but needs a metaphysics on which to support itself, whatever fine airs it may assume towards the latter.

It is only a man's own fundamental thoughts that have truth and life in them.

What a man can do and suffer is unknown to himself till some occasion presents itself which draws out the hidden power. Just as one sees not in the water of an unruffled pond the fury and roar with which it can dash down a steep rock without injury to itself, or how high it is capable of rising; or as little as one can suspect the latent heat in ice-cold water.