I don’t remember spoilers - in general I wouldn’t worry about them for things like Paradise Lost or Dante anyway.

My memory may be betraying me - I was a kid when they came out - but my memory is off reading the first one shortly after it came out with no context that it was the new big thing and then a few months later it being this big sensation. My understanding is it became a big deal by word of mouth first and then the publishers caught up and magnified that