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.
Authentication Score 2
Original Citation
Nietzsche, Friedrich. Jenseits von Gut und Böse: Vorspiel einer Philosophie der Zukunft [Beyond Good and Evil: Prelude to a Philosophy of the Future]. Leipzig: C. G. Naumann, 1886, ch. 4, no. 146.
Current Citation
Nietzsche, Friedrich. Beyond Good and Evil, translated by R. J. Hollingdale. Penguin Classics, 2003, ch. 4, no. 146.