A writer always wants their readers to be saying “and what happens next?!?” TV writers have known about this for decades. It is called the cliff-hanger. A drama series with a cold-opening (i.e. a scene before the opening credits) will have a cliff-hanger of some sort. It will ask questions without giving answers. It invites the viewer to keep watching if only to scratch that itch of not knowing why.
This trick of not telling the audience something can also be used in a different way. The popular website TV Tropes has a term called The Noodle Incident. This originated in the comic strip Calvin Hobbes and originally referred to an incident where Calvin got into so much trouble at school he refuses to talk about it. And they had to call the emergency services. Bill Waterson wisely left it unexplained, because in the readers’ minds “it would undoubtedly be more outrageous”, as he put it. The trope is similar: it refers to an incident that is off-stage or off-camera that the characters know about and refer to, but do not explain to the audience. We get to see how characters are defined by their reaction to this piece of unreported backstory.
Of course, some writers cannot help themselves. They just can’t leave things unexplained.
One of the most infamous in movie history is what George Lucas did in the first Stars Wars prequel movie (The Phantom Menace). He introduced the idea of midichlorians as a measurable aspect of the source of The Force. Many in the fanbase derided this and the consensus amongst fans seems to be this was a bad idea. We didn’t need Lucas to explain The Force. This was an anti-Reveal: he tried to explain a Noodle Incident.
David Eddings was prone to it, too. His last three works in the world of the Belgariad were new narratives about Belgarath, Polgara and then an organised subset of his world-building notes. In a lot of ways, the backstories of Belgarath his daughter Polgara were long explanations of Noodle Incidents. We didn’t really need them. The crumbs of both distributed throughout the main stories of the Belgariad and then the Mallorean were more than enough, in my opinion. And Eddings actually telling them diluted their magic as characters. They were anti-Reveals.
In popular TV cult culture, we are on the brink of what could be another. The season finale of series 7 of Doctor Who is a portentious example. It has been titled The Name Of The Doctor. But one thing throughout all fifty years of Doctor Who that we never ever ever discover is the Doctor’s name. He is always known as “The Doctor”. With few exceptions, he introduces himself as “The Doctor”. (If he must use an alias, he usually chooses “John Smith”.) He actually goes out of his way to not reveal his own name. And now we have an episode that is devoted to this most iconic of unrevelable facts.
To be sure, there are people in the Who universe who know his name. His sometime wife River Song seems to know his name. Viewers are fairly sure we’ve seen it written down on-screen, albeit in Gallifreyan script that no-one seems to have decoded.
But does the viewing public need to know? Do we even want to know? I don’t think we do.
Steven Moffat has a chance to completely balls up the franchise by revealing a piece of lore that the original creators and their successors didn’t deem revealable. However, I don’t think he will. Waterson, Lucas and Eddings at least all had the luxury that it was their own franchise they would be damaging. Moffat doesn’t.
Moffat has been doing some creative things in the Who universe. The are snippets of advanced future societies that we see the likes of River Song be involved with. The Doctor, too, and out of these we have some marvellous recurring characters like Dorian Maldovar.
And then there’s the prophecy. This episode looks like it will tell us about more about that prophecy. But some things aren’t meant to be revealed. Like the Doctor’s name.