Nietzsche was expressing the thought that only the strongest were equipped to face the constant inner struggle that marks even our most “peaceful” moments. The struggle is one of competing drives. Morality and reason are influenced by and find their expression in the results of this conflict. Realizing the magnitude of this inner struggle, Nietzsche states: “He who fights with monsters might take care lest he thereby becomes a monster. And when you gaze into an abyss the abyss also gazes into you.”
Reasoning from Nietzsche’s point of view, you may think you are brave and clever and can stare straight at the hardest questions.
After breaking down layer after layer of ego you may begin to see the truth.
An abyss is the absence of something. More than that, it’s an absence that absorbs any reflection of any “something” that tries to interact with it.
“You” are a “something”.
Staring into an abyss is an interaction between something and nothing. If the nothing is deep enough it calls into question the existence of the something.
The universe is cold and alone and asking you for answers just as much as you are asking it, and this is a terrifying revelation indeed.
Realizing you are that something, that something anchoring the nothingness, that sanity anchoring the insanity, that warmth anchoring the cold, substance anchoring the void, that is a heavy burden.
When you reach those darkest moments life has to offer, when you are pushed out of your comfort zone and reach those moments where you are not sure what to say, or how to act your true nature comes out. When you stare into those dark moments, when no social precondition is tellin you how to act your true nature comes out.