That we are living in a book. Note that the popular plot device of being trapped in one (or more) books survived intact as being trapped in the TV and being trapped in a virtual reality game.
If you watch kid's cartoon series, you know that this plot device is as inevitable as the Freaky Friday contrivance.
Yeah, that's precisely the point I was trying to make (I think). It's the same basic mental model, "we ARE the technology we use." As it evolves, so does the theory.