“He who fights with monsters should look to it that he himself does not become a monster. And if you gaze long into an abyss, the abyss also gazes into you.”
— Friedrich Nietzsche, Beyond Good and Evil, §146
What this quote means
A warning about moral contamination and the unconscious: in opposing evil we risk adopting its methods, and prolonged contemplation of darkness changes the observer. It anticipates Jung’s concept of the Shadow.
The idea behind it
The Shadow — Jung's term for the disowned parts of the self — traits we deny and project onto others — which must be integrated to become whole.
Beyond Good and Evil is public domain; attribution verified. Confidence: high.