Capitalist societies can always heave a sigh of relief and say to themselves: communism is finished since the collapse of the totalitarianism of the twentieth century and not only is it finished, but it did not take place, it was only a ghost. They do no more than disavow the undeniable itself: a ghost never dies, it remains always to come and to come-back.

That's Derrida in Specters of Marx (page 123). Hauntology is such a cool topic. I actually wrote a thing on climate change and hauntology, using a Marxist lens with a little help from Derrida if that's interesting to you! Pretty spooky stuff.