A thinker sees his own actions as experiments and questions--as attempts to find out something. Success and failure are for him answers above all.

He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you.

Maturity consists in having rediscovered the seriousness one had as a child at play.

Be nice to people on your way up because you'll need them on your way down.