A spectre is haunting Europe — the spectre of communism. So begins the Communist Manifesto and Marx was right - Communism was a spectre, in the sense of being non existent but causing fear. I stole this idea from AJP Taylor.
Now the spectre that hunts the developed world is Nazism, which is an even less real danger than Communism was in 1848.
Yet this fear is being like the Nazis, in some way or another, is remaking the world.
Of course nonexistent dangers can become real one day - as happened in Russia almost 70 years after Marx wrote, thanks to the cunning of Lenin. Mussolini's fascism or Nazism won't come back, but some extremist ideology might somehow rise from the dead. The liberals of all parties who rule the developed world seem to be doing everything they can to make this possible.