He who fights with monsters should be careful lest he thereby become a monster.

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  If you gaze long into an abyss, the abyss also gazes into you.

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  He who has a why to live can bear almost any how.

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  What does not kill me makes me stronger.

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  Whoever has ever built a new heaven found the strength for it only in his own hell.

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  One must be a sea to be able to receive a polluted stream without becoming unclean.

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  The most common lie is the one with which a man deceives himself.

All aphorisms