The following excerpts are from the maestro himself...
Most good â€œfairy-storiesâ€ are about the adventures of men in the Perilous Realm or upon its shadowy marches. Naturally so; for if elves are true, and really exist independently of our tales about them, then this also is certainly true: elves are not primarily concerned with us, nor we with them.
And lastly there is the oldest and deepest desire, the Great Escape: the Escape from Death. Fairy-stories provide many examples and modes of thisâ€”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.