Also how about that quote at the start. Unfortunately it’s not Twain according to this site - actually Friedrich Nietzche.
“He who fights with monsters should look to it that he himself does not become a monster.
And when you gaze long into an abyss the abyss also gazes into you.”
https://bookstr.com/list/10-famous-mark-twain-quotes-that-he-never-said/