Before we blame we should first see whether we cannot excuse.

One might call habit a moral friction: something that prevents the mind from gliding over things but connects it with them and makes it hard for it to free itself from them.

The worst thing you can possibly do is worrying and thinking about what you could have done.

Just as the performance of the vilest and most wicked deeds requires spirit and talent, so even the greatest demand a certain insensitivity which under other circumstances we would call stupidity.

Bad writers are those who try to express their own feeble ideas in the language of good ones.

All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty. They give me no pleasure. They are merely auxiliaries. At close range it is all not true.

It often takes more courage to change one's opinion than to stick to it.