Milton's alluding to what he took to be the divinely inspired prophesy of Saint John the divine that ends the New Testament.

But John Milton is also recompensed and, by the weird sacrificial logic that Saint Peter has already sketched out for us, you can see a really disturbing way in which Milton has benefited as well.

On the one hand, he is exactly the sort of saint Pope John Paul approves of: a person imbued with charisma who has achieved enough remarkable feats to keep the faithful talking for a very long time.