If I ever write a story, it will be about immortality. I love the phrase he uses here: The fugitive spirit.
…lastly there is the oldest and deepest desire, the Great Escape: the Escape from Death. Fairy-stories provide many examples and modes of this—which might be called the genuine escapist, or (I would say) fugitive spirit. But so do other stories (notably those of scientific inspiration), and so do other studies. Fairy-stories are made by men not by fairies. The Human-stories of the elves are doubtless full of the Escape from Deathlessness. But our stories cannot be expected always to rise above our common level. They often do. Few lessons are taught more clearly in them than the burden of that kind of immortality, or rather endless serial living, to which the “fugitive” would fly. For the fairy-story is specially apt to teach such things, of old and still today.
-J.R.R. Tolkien, On Fairy-Stories, (Recovery, Escape, Consolation)