Battle not with monsters lest you become one.

Battle not with monsters lest ye become a monster and if you gaze into the abyss the abyss gazes into you.

Whoever fights monsters should see to it that in the process he doesn't become a monster

One is not free to become a Christian. One must be sick enough for it.

Whoever battles with monsters had better see that it does not turn him into a monster. And if you gaze long into an abyss, the abyss will gaze back into you.

He who fights with monsters might take care lest he thereby become a monster. Is not life a hundred times too short for us to bore ourselves?