[[WMG: ''Literature/ACanticleForLeibowitz'' is set in the past of the ''Franchise/{{Dune}}'' Universe.]]

Dune is set ~10,000 years in the future. Canticle takes up 1,200 of that. The "Butlerian Jihad", in which humans got rid of computers sounds a lot like The Simplification. While the two were not the same event, the history of Canticle likes repeating itself.
* Oddly enough, this makes sense...as the humans in ''Dune'' aren't aware of where Earth is anymore (possibly because the knowledge was lost/deliberately suppressed in order to give humanity a fresh start) and the Bene Gesserit, while being an exclusively female religious order, are run much like the Jesuits (possibly because their origins lie with the original church-sponsored colony ship).

[[WMG: ''Film/TheBookOfEli'' is set in the past of ''Literature/ACanticleForLeibowitz''.]]

It takes place before or during The Simplification. Either Alcatraz was eventually destroyed, or it managed to stay secret until after the first and second parts of the book.

[[WMG: ''Literature/ACanticleForLeibowitz'' is set in the past of the '''''{{Simoun}}''''' universe.]]

See the ''{{Simoun}}'' WMG page for details.

[[WMG: The world of ''Literature/ACanticleForLeibowitz'' is not our future. It's our distant past.]]

The world of the book is simply too different from ours. There are immortal beings and mutated zombies, and what appear to be [[spoiler: psychic powers]]. When the [[spoiler: second]] [[ApocalypseHow nuclear war destroyed the world]], the [[FlingALightIntoTheFuture ship of refugees that was sent out to preserve mankind]] landed on a [[AllPlanetsAreEarthlike conveniently habitable planet]] which was then named after EarthThatWas. Thanks to EternalRecurrence, our present civilization ended up [[FantasyCounterpartCulture taking on more than a few features of theirs]], minus the MedievalStasis. Of course, [[FutureImperfect history has become so muddled over time]] that our origins have been [[LostForever long since forgotten]], but the story was [[LiteraryAgentHypothesis preserved in a chronicle of the events]] by an obscure author who never wrote anything else.

Oh, and Benjamin? [[SnarkBait He's dead.]] Atomic blast hit him. Nothing could be done.

[[WMG: Benjamin ''is'' Leibowitz]]

He is the WanderingJew, destined to WalkTheEarth until the return of Christ. Which is why he's still hanging around at the end. And while he claims that Leibowitz is a "distant relative," this is more to keep people from hounding him to the ends of the earth and partly to bury that part of his life with his long-dead wife, Emma/Emily.

[[WMG: Not only is Benjamin (aka the Old Jew) Leibowitz, but he also set up his own canonization through the buried shelter Francis "finds."]]

While he likely long reverted to Judaism by the time "Fiat Homo" takes place, he knew that in order to guarantee the survival of both the Memorabilia he started and the abbey protecting it, he (as "Leibowitz") would have to be canonized by the Catholic Church. And what better way to ensure said canonization than to reveal to a young monk named Francis the location of a half-buried shelter containing his "relics."

It's also possible that he did this as well to confirm that the shelter in question really was where Emily, aka Emma Leibowitz finally died, and thus put one ghost of the past to rest.