Antithesis is the narrow gateway through which error most prefers to worm its way towards truth.

The destiny of the human race is to widen the gap separating it from the lower races of animals. Any code of morality which retains its permanence and authority after the conditions of existence which gave rise to it have changed, works against this upward progress of man.

I teach the No to all that makes weak--that exhausts. I teach the Yes to all that strengthens, that stores up strength, that pride.

Whoever despises himself nonetheless respects himself as one who despises.

Why is it that wellnesses are not as contagious as illnesses--generally speaking, but also especially regarding taste? Or are there epidemics of health?

A degree of culture, and assuredly a very high one, is attained when man rises above superstitions and religious notions and fears, and, for instance, no longer believes in guardian angels or in original sin, and has also ceased to talk of the salvation of his soul.

I am affected, not because you have deceived me, but because I can no longer believe in you.