In my earlier posts about entering the worlds of movies and the pull this exerts on the imagination I looked closer at the fascination we might feel with this idea.
So, as I wrote, the worlds of some movies exert a pull on the imagination; but there is no way to satisfy the desire, no way to go in and follow up. So what does the movie do? It 'knows' about that desire and 'satisfies' it, by giving it expression, playing it out. In the movies, everything is possible, including entering a movie plot. So in the world of a movie (such as Die Einsteiger), a device is conjured up that fulfills the desire. It's not different from many other wish-fulfilling machines (or from wish-fulfilling magic). The worlds of fiction are in part intended to act out fantasies in which desires are fulfilled. Thus the idea of a passage into the unreal is born.
Note that this is in some sense a reflective process: fiction, as it were, self-consciously exploits a desire which it itself has helped to generate in the first place. But we must be careful not to make too much out of this reflexive constellation. People in movies don't just travel into the worlds of fictions, but also into dreams, or the past and the future. It's not the reflexivity that makes this work; that's not even a necessary attribute. It is merely a spicy extra feature in the particular constellation in which the world from which departure is taken and the destination world are both instances of the same form of unreality (i.e., worlds of movies).
There seems to be one thing that is required, though. In the real world, it's not possible to travel into the world of a movie, a dream, or the past or the future. In the real world, there is no magic, and neither are there any technical devices (at least up to now) which can do the trick. And therefore we (real people) cannot make any such journey. The only people who can are fictional characters, people who are already part of the world of a movie (or other fiction, such as a novel). The starting point of any passage into the unreal must lie within an instance of unreality already. The laws that govern the real world don't allow for it (as far as we know), but the laws that govern any world of fiction can be adjusted by the creator of that world, the person who imagines it, and so an instance of unreality might allow traveling into those worlds of fictions, dreams, or the past and the future. Note that this means that passage is always a matter of going into the world of a nested fiction. There is no way into fiction; just into fiction-within-fiction.
(It's an interesting question exactly how far this can be generalized: there seems to be a passage from fiction into dreams, and the past or the future; maybe there's a path from dreams into fiction, or again the past or the future; there might be dreams-within-dreams into which we can travel from dreams. There seems to be no passage from either the past or the future to anywhere — what does this tell us about the differences between these forms of unreality?)
Such fiction-within-fiction is not exactly a rare phenomenon. There is nothing unusual for people in novels to read books or watch movies, or for film characters to do the same. After all, the characters in those novels or films are often intended to appear much like people in the real world, and consuming fiction is something that people in the real world do. Sometimes, fiction-within-fiction has a more substantial role to play than just making characters seem like real people. In Shakespeare's Hamlet, the Danish prince uses a play to confront another character with a story very similar to what he thinks might have been enacted by his uncle. In other words, Hamlet uses the play-within-a-play as a means of indirect communication, and something that is intended to awaken emotions and provoke a reaction.
In any case, however, this nesting of fiction-within-fiction is necessary for passage into the unreal: there is no traveling into fiction unless you are already within a fiction.