Where do prophecies come from?

• The idea of Time itself designating some people and events as Important and composing vague poetry about them is incompatible with a universe that runs on simple physical laws and is obviously nonsense. Doubly so if those laws are actually timeless. I hope I can state this unequivocally.

• If Eliezer wants to teach his readers that a hero can be anyone with the talent, courage, and conscientiousness to do what's right, that there are no auras of destiny, that heroes choose themselves, then he can't actually have the planet's operating system, the Source of Magic, amputating the characters' destinies by choosing which ones to promote to Power User status. Even if it has a naturalistic explanation, a story whose heroes are ordained by fate would teach the same lessons as Star Wars. While David Brin is reading it. And Eliezer wouldn't do that, right?

Dunno.

• Depending on where you draw the line, anywhere from four to six false prophets have now appeared in the story. I assumed they were there to prime you - really, beat you over the head - with the idea that prophecies can be human fabrications. But perhaps Eliezer just likes to repeat himself.

• Similarly, the repetition of Grindelwald's name should be priming us to accept his subsequent appearance in the story and not find it arbitrary or contrived. Chapter 42 is utterly pointless except as foreshadowing of his motivation for returning. If Trelawney's prophecies have a human author, it should be someone who can play at the same level as Dumbledore and Voldemort, but not be one of the prophecies' dupes. Grindelwald is the only available candidate. It fits the rhythm of the story, which is pounded out with falling anvils: Harry being forced to fight Voldemort and Grindelwald at the same time is the sort of escalation of challenge he faces routinely. It's a reasonable guess.

But there's nothing connecting Grindelwald to prophecy. And I was wrong the last time I guessed at his role in the story, trying to shoehorn him into Voldemort's superfluous second secret identity, Mr Hat and Cloak. So I don't know. Where do prophecies come from?