本句出自尼采的Jenseits von Gut und Böse（Beyond Good and Evil,《善与恶的超越》）（1886）。
原文是德文：
Wer mit Ungeheuern kämpft, mag zusehn, dass er nicht dabei zum Ungeheuer wird. Und wenn du lange in einen Abgrund blickst, blickt der Abgrund auch in dich hinein.
英文译本有：
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.
He who fights with monsters should be careful lest he thereby become a monster. And if thou gaze long into an abyss, the abyss will also gaze into thee.
Beware that, when fighting monsters, you yourself do not become a monster... for when you gaze long into the abyss, the abyss gazes also into you.
——Friedrich Nietzsche
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这句中文既然不署尼采的名，那就不是以“译文”的身份出现，但绝对是在尼采原句上做了演绎的结果。
