It’s basically about how bad things can happen repeatedly in history, even if people knew those things were bad the first time around. It may simply look different enough so people don’t take it seriously the second time around, maybe seem not as threatening or even ridiculous, but it ends up causing the same kind of harm. But that second time is no longer a tragedy - because a tragedy is basically something that takes the world by surprise and has horrible effects. Marx calls the second time a “farce” - it’s something that is ridiculous and avoidable and stupid and by all accounts everyone should have prevented it from happening.

“Hegel remarks somewhere that all great world-historic facts and personages appear, so to speak, twice. He forgot to add: the first time as tragedy, the second time as farce.” - Karl Marx, “The Eighteenth Brumaire of Louis Bonaparte”

Great quote. But sometimes I think “twice” was overly optimistic.