Uh... what rule?
Maybe I transcended something.
Back on topic before an axe falls... I was thinking more about the Millegory.
On the far side of the mill, you are once again looking at "our reality", as in our physical world-- but with a changed perspective. (Through a glass, darkly?) You are seeing what is there after having seen what's inside the mill. Going by OnFaeryStories, I'm guessing Tolkien would enjoy that. You're also seeing what the other side of the mill would look like from inside the mill; as if you are looking at the real world from Faeryland... which I guess Tolkien would also appreciate.
As a small example, how many people have a deeper appreciation for trees, having read the trilogy? I do; and I know when it began. On Cerin Amroth, when Frodo touched the bark of the tree, I got a glimpse of what one of my own trees, and Trees in general, Truly is/are-- just a small glimpse, but it began something. And I've been looking at my own trees and other trees differently ever since.