Every attainment, every step forward in knowledge, follows from courage, from hardness against oneself, from cleanliness in relation to oneself.

Man is at his furthest remove from the animal as a child, his intellect most human. With his fifteenth year and puberty he comes astep closer to the animal; with the sense of possessions of his thirties (the median line between laziness and greediness), still another step. In his sixtieth year of life he frequently loses his modesty as well, then the septuagenarian steps up to us as a completely unmasked beast: one need only look at the eyes and the teeth.

There is one thing one has to have either a soul that is cheerful by nature, or a soul made cheerful by work, love, art, and knowledge.

Where the good begins.- Where the poor power of the eye can no longer see the evil impulse as such because it has become too subtle, man posits the realm of goodness; and the feeling that we have now entered the realm of goodness excites all those impulses which had been threatened and limited by the evil impulses, like the feeling of security, of comfort, of benevolence. Hence, the duller the eye, the more extensive the good. Hence the eternal cheerfulness of the common people and of children. Hence the gloominess and grief - akin to a bad conscience - of the great thinkers.

When a man reaches his maturity in understanding and in years, the feeling comes over him that his father was wrong to beget him.

Only ideas won by walking have any value.

Let us beware of saying that death is the opposite of life. The living being is only a species of the dead, and a very rare species.