A mysterious limbo realm in C.S. Lewis' The Magician's Nephew, one of The Chronicles of Narnia. The Wood between the Worlds is an endless forest where nothing happens and no animal lives (except for an old guinea pig once transported there). Among the trees are many pools of water just a couple of inches deep. When wearing the proper magic rings, a person can travel from world to world by emerging from and descending into the pools. When a world dies, as Charn did, its pool dries up. Professor Digory Kirke and Polly Plummer discovered the land of Narnia when they were children by visiting the Wood.

Every once in a while, while reading a fiction book (usually a fantasy book), I come across a place where I realize the author is not making stuff up. There is a rich trove of fantasy tropes to include from previous works, and normal creativity and imagination can provide for some nice pyrotechnics. But every once in a while something works its way into a work that shows that the author really, truly, had a direct experience of something, rather than thinking it would be a nice thing to entertain his readers with. This is what I thought of, for example, when I read about the pendulum and the Hour Lillies in Michael Ende's Momo.

C.S Lewis has a mixed reputation amongst geeks. On one hand, we all grew up reading Narnia, and they provide a cornerstone for fantasy authors and readers. On the other hand, his books were Christian allegories that many find pedantic to the point of propaganda. As for his imagery, most of it seems to be lifted from other sources and presented for narrative effect. His cosmology seems to be cribbed from The Bible and Neo-Platonism.

Which is why the Wood Between the Worlds, the dreamy, never-ending forest featured in the series sixth book (by external chronology, the first by internal chronology) jumps out at me. All the other cosmological locations in the book, such as Aslan's Country, seem to have been constructed as allegories first, and then worked out narratively second. The Wood Between the Worlds strikes me as something that was actually experienced---I wouldn't claim as an actual full on hallucination, but was seen as a creative vision, as an actual way the universe(s) might work, and included in the work because it seems real. Of course, I don't have any proof of this, other than the fact that the idea of floating far above the world, where not just this universe but all universes tend to blur together far below, is one I have heard before in people's visions, especially those inspired by truly bizarre substances. The other reason it comes across as real is just how well described the setting and character's reactions to it are. It seems that Lewis was actually enjoying writing this scene in a way that he wasn't with other scenes in the books.

Of course, none of this is proof, and it might just reflect my own memories and interpretations of the book. The lassitude and dreaminess of the Wood reminds me of endless afternoons in my father's garret, reading fantasy books and sketching on scrap paper. Even those who don't believe that the Wood was a rare intrustion of mysticism into Lewis' Cambridge rationalism will probably agree that the scene and setting does stand out.

I largely agree with glowing fish. I obsessed over The Magician's Nephew like no other book when I read it in 3rd grade. Much more so than the other Narnia books. It appears that The Wood Between the Worlds does indeed represent a profound concept of a Multiverse, and possibly derives from a real mystical experience. Quoting CSL:

"as in the sinless world beyond the horrors of animal and human life;
in the behaviour of stars and trees and water, in sunrise and
wind. may there be here (in my heart) a like beauty"

the novel "The Wood Beyond the World" may have offered inspiration. he expresses a lot of interest and thought about mystic travel. This quote from Letters to Malcolm:

"I do not at all regard mystical experience as illusion. I think it shows
that there is a way to go, before death, out of what may be called
"this world"--out of the stage set."

"The lawfulness, safety, and utility of the mystical voyage depends not
at all on its being mystical — that is, on its being a departure — but
on the motives, skill, and constancy of the voyager, and on the grace
of God."

Now, glowing fish mentioned that this type of experience is not atypical of what one might experience on drugs. I have been told by a friend that after smoking Salvia Divinorum he had felt like he was in The Wood linking to all worlds from the Narnia book. My best efforts have been unsuccessful to recreate this experience myself. My experimentation with Ketamine was far more enlightening. Take this last quote from Lewis himself:

"I shouldn't be at all disturbed if it could be shown that a
diabolical mysticism, or drugs, produced experiences indistinguishable
(by introspection) from those of the great mystics. Departures are all
alike; it is the landfall that crowns the voyage."

Lewis goes on a bit about his desire to look behind the scenes of the stage set of our world. Whether or not "The Wood Between the Worlds" stems
from a real experience or merely a fictional construct, it has left a mark on my view of reality.