Apocalypse and revelation mean the same thing twice. Of course both refer to the end times; but furthermore, etymologically, apocalypse comes from kaluptein (“to cover”; caul has the same root—eucalyptus just means “well-covered”) with the negating prefix apo. An apocalypse is an uncovering, a revealing—see what I’m doing here?—a revelation.
Theoretically, anything about the future, good or bad, could be revealed, but, as Isaac Bashevis Singer once wrote, “If you keep on saying things are going to be bad, you have a good chance of being a prophet.” So we get what we get. We get apocalypse; we get Revelation.
Many apocalyptic texts (I’m taking this mostly from Alexander’s The Byzantine Apocalyptic Tradition) assert their authority by prophesying the near-future before moving on the the eschaton. The problem is, of course, that the near-future is hard to predict, so apocalyptic writers did what anyone would in that situation: they decided to fake it.
What you do is choose some big recent events that would have been hard to predict—say, WWII, the moon landing, 9/11, and Go Set a Watchman—put them in your text as a lead up, and then attribute your text to Harry Houdini, who died an 1926. Then everyone says, “How did Houdini predict the moon landing?!? OMG, the rest is going to be right, too!”
Textual historians date apocalyptic literature, in the absence of better evidence, based on the last correct prediction. Whenever it was written, it has to be after that date!
The prediction after the last correct prediction is usually something like “and then everything ends,” which of course is precisely what has not happened. So apocalyptic literature is correct up to the point where it begins to be useful, whereupon it falls apart.
It should be noted that “precisely what has not happened” is not an uncontroversial statement: In 1923, for example, a movement called (presumably only by non-members) the Vailala Madness swept the New Hebrides. It promised a coming apocalypse, after which dead ancestors would return in boats, bearing gifts. In 1934 some anthropologists asked the Melanesians what had ever happened to the coming apocalypse, and they were told that it had come. People remembered quite clearly the earthquakes, the floods, the plants blooming miraculously overnight, the walking dead who came and left in their boats.
Analogous is the Christian school of Preterism, popular in the nineteenth century, which holds that all bible prophesies have already come to pass, the last prophesied event generally being the destruction of the Temple in A.D. 70 (some Preterists pick different events and dates, but this is a common one). We are therefore quite literally living in the Kingdom.
The apocalyptic biblical prophesy of Revelation was written after A.D. 70, so the date works out too!
I don’t remember any ancestors returning from the dead, of course, but sometimes something even better than people comes back. I’m talking about texts, of course, and history is filled with long-lost texts, hinted at in surviving fragments, that show up eventually. The Dead Sea Scrolls are the most famous such recovery, but there are many others, and among them two of my favorite apocalypses.
The Book of Enoch, quoted in the bible and known since antiquity, was lost, outside of Ethiopia, and did not get rediscovered again until the eighteenth century. In the Ethiopian Church (which has the longest bible of any Christian denomination), it had always been a canonical book, which is why it was preserved there, in a Ge’ez translation.
(Enoch therefore joins that rare set of books known only through translation, alongside the Gospel of Mark, much of Averroes, portions of Jan Potocki’s MS. Found in Saragossa, and until recently Arthur Koestler’s Darkness at Noon. Sometimes people like to indulge in the fantasy that most works of Aristotle only exist because of Arabic translations; this isn’t true, which is why the Loeb classics have so many volumes of Aristotle in Greek, but it’s inspired by truth in the sense that depending where and when you lived it might have been easier to get Aristotle in a retranslation than the original.)
It’s not that the Book of Enoch is never scary — it would be a rare apocalypse that is never scary — but it also contains a millennial promise designed to be most comforting to a collector of old books or comics: “And from that time on there will be nothing that will be destroyed…” (69:29a).
Best of all apocalypses, though is The Apocalypse of Adam, from the Nag Hammadi library. Here, back in time near the dawn of creation, Adam warns his surviving son, Seth, of, among other things, that most troubling of (for them) future events, the most famous destruction of the world — the upcoming flood of Noah.