I am fully convinced that the soul is indestructible, and its activity will continue through eternity.

All ages have said and repeated that one should strive to know one's self. This is a strange demand which no one up to now has measured up to and, strictly considered, no one should. With all their study and effort, people are directed to what is outside, to the world about them, and they are kept busy coming to know this and to master it to the extent that their purposes require. . . . How can you come to know yourself? Never by thinking, always by doing. Try to do your duty, and you'll know right away what you amount to. And what is your duty? Whatever the day calls for.

Every decided colour does a certain violence to the eye, and forces the organ to opposition.

We are pantheists when we study nature, polytheists when we write poetry, monotheists in our morality.

[W]hat counts is that one perceives excellence and dares to give it expression, which sounds little but is in fact a great deal.

Beware of wishing for anything in youth, because you will get it in middle age.

Everything factual is, in a sense, theory. The blue of the sky exhibits the basic laws of chromatics. There is no sense in looking for something behind phenomena: they are theory.