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.
Friedrich Nietzsche, Beyond Good and Evil, Aphorism 146
German philosopher (1844 - 1900)
怪物と闘う者は、その過程で自らが怪物と化さぬよう心せよ。おまえが長く深淵を覗くならば、深淵もまた等しくおまえを見返すのだ。