I was watching Serenity yesterday and I wished that Joss Whedon had continued on with the story, either with more movies or with several years of a series like Firefly. I've had a similar but much greater experience with the fantasy of JRR Tolkien, where I'll be deep in Middle Earth journeying along with four hobbits, an elf, a dwarf, and three men... and never want to leave. When I do "come back" as it were I feel like the world I inhabit is somehow less "real" than the world I left. Now, I know that Lewis' quote above needs to be taken with a grain of salt, for not all desires speak to the design of the Creator, but this desire of finding the really real, of living in a world that speaks to the soul more easily than the one we currently inhabit, of understanding the beauty of existence more tacitly than the honking, green-back, work-a-day world we become so immune to does seem to point to something inherent to our humanity.
The Mission, a movie about the Jesuits in South America has a insightful dialog dealing directly with this point:
Hontar: We must work in the world, your eminence. The world is thus.
Altamirano: No, Señor Hontar. Thus have we made the world... thus have I made it.
We make the world as much as we are made by the world, it is so easy to write off the sufferings we encounter in daily life as not caused by us but by the society, another person, the president, our boss, God... but when it comes down to it: We are the ones responsible. Fantasy illustrates this point by realizing the desire within us for a beauty, a culture, a reality that is more real than the one we have helped create. Fantasy lets us have a comparison for the reality around us to what it can be in opposition to what it is, either for better or worse. For there are fantasies that let us realize how good we have it, not only how much we miss.
Inasmuch as we have a yearning for these "other worlds" I think that, in a sense, we will experience them in Heaven. Just as beauty, music, art, people, sex, good food, exercise, friends, and everything else that acts as a finger pointing to the moon will exist in Heaven inasmuch as it is good, so too I think that I will meet Gandalf, Merry, Pippin, Digory, Mr. Vane, Lilith, and Bombadil. Not necessarily in the sense of meeting the persons themselves but rather, the yearning that I have to meet them will be satisfied as much (and more) as if I had met them. For I will know Gandalf as Tolkien knows him, I will know Digory as Lewis knows him, I will know Lilith as MacDonald knows her, because I will know them better in Heaven than I know anyone here on earth.
If you haven't read Tolkien's "On Fairy Stories" do yourself a favor and look it up; it is pure delight and helps us understand those odd people dressed up with hairy feet, Trekkie uniforms, or glasses and lightning bolts.