[abjimsnm] gaze into the abyss

some German spelling variations in a famous quote from Beyond Good and Evil (Jenseits von Gut und Böse) (1886) by Friedrich Nietzsche:

Wer mit Ungeheuern kämpft, mag zusehn/zusehen, dass/daß er nicht dabei zum Ungeheuer wird.  Und wenn du lange in einen Abgrund blickst, blickt der Abgrund auch in dich hinein.

dass/daß is eszett (sharp s).  daß is probably more correct, but dass seems more common in collections of quotes.  what was German orthography in 1886?

zusehen seems to be more correct, but zusehn seems to be a valid archaic spelling.

the quote comes from a chapter of sayings and provides no further context.  in reality, becoming a monster is complicated (investigated by Zimbardo and many others), and probably requires much, much more than just gazing into the abyss.  though perhaps Zimbardo gazed into the abyss too long himself, becoming evil.

I like the alternate translation "stare into the void; the void stares back", though that changes the meaning.  "abyss" implies looking downward, toward evil, whereas "void" makes no ethical or moral judgment.  and I like the weirdness of the void (nothingness) staring back, in contrast to the (implied) monsters of the abyss staring back.  does spending mental effort on a subject seemingly devoid of ethical and moral issues (e.g., mathematics) turn you evil?