I’m presently rereading The Fellowship of the Ring. I mentioned this to my Facebook peeps earlier in the week, mostly because I wanted to slag on the Tom Bombadil section of the story. (In my defense, I feel it's a narrative momentum killer; it just goes on and on, and doesn’t seem to contribute much to the greater story.)
But as I read the book this time—including the Bombadil stuff—I've realized that I've personally never read books set in a fictional world that are as convincingly “real” as Middle-earth.
Most writers (and I’m one of these) usually create fictional settings that stand up to what I call the “3 or 4 Rule” of reader scrutiny. Meaning, the book asserts something unique about its setting that’s notably different from the world as we know it, and then savvily provides answers—either explicitly on-page, or implied—that can satisfactorily survive about three or four levels of “But if that’s true, then what about…?” questioning that readers may have about that unique element.
(I reckon that for most readers, this all happens under the hood; they may not even be aware that they're asking these questions or reading their answers. Generally, once the story survives this sniff test, readers go along for the ride. Smart authors understand this and—when things are really popping—proactively address those questions along the way, often on the sly. Like a magic trick.)
But Tolkien’s world doesn’t satisfy just a few levels of interrogation. It’s got an answer for everything, and it all goes hundreds of miles down. Every-damned-thing has a history (often implied more than outright stated), every culture is authentically different from each other, and the foundations for so many of the big set pieces in the story (such as the fellowship’s trek into Khazad-dûm, which is where I am right now in the book) are exquisitely foreshadowed in plain sight far earlier in the story.
The in-world songs and poetry, as much as I fuss about them, are wonderful examples of this. Lore is everywhere in these books. You can’t help but breathe it in.
When I read Fellowship, I’m not reading a story. I am truly visiting a place … a place so brilliantly invented and presented, I’d swear it as real as my backyard.