Man's maturity: to have regained the seriousness that he had as a child at play.

Science ... has no consideration for ultimate purposes, any more than Nature has, but just as the latter occasionally achieves things of the greatest suitableness without intending to do so, so also true science, as the imitator of nature in ideas, will occasionally and in many ways further the usefulness and welfare of man,-but also without intending to do so.

The scaffolding must be removed once the house is built.

Since Copernicus, man seems to have got himself on an inclined plane-now he is slipping faster and faster away from the center into-what? into nothingness? into a 'penetrating sense of his nothingness?' ... all science, natural as well as unnatural-which is what I call the self-critique of knowledge-has at present the object of dissuading man from his former respect for himself, as if this had been but a piece of bizarre conceit.

All names of good and evil are images; they do not speak out, they only hint. He is a fool who seeks knowledge from them.

On every parable you ride to every truth.

Marriage was contrived for ordinary people, for people who are capable of neither great love nor great friendship, which is to say, for most people--but also for those exceptionally rare ones who are capable of love as well as of friendship.