My humanity is a constant self-overcoming.

Marriage marks the end of many short follies - being one long stupidity.

He who fights with monsters might take care lest he thereby become a monster. Is not life a hundred times too short for us to bore ourselves?

If you know the why, you can live any how.

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

For the longest time, marriage has had a guilty conscience about itself. Should we believe it?--Yes, we should believe it.

Go through the moral demands...one by one and you will find that man could not live up to them; the intention is not that he should become more moral, but that he should feel as sinful as possible. If man had failed to find this feeling pleasant - why should he have engendered such an idea and adhered to it for so long?... Man was by every means to be made sinful and thereby become excited, animated, enlivened in general. To excite, animate, enliven at any price.