...The peculiar quality of the 'joy' in successful Fantasy can thus be explained as a sudden glimpse of the underlying reality or truth. It is not only a 'consolation' for the sorrow of this world, but a satisfaction, and an answer to that question, 'Is it true?' ...
I would venture to say that approaching the Christian Story from this direction, it has long been my feeling (a joyous feeling) that God redeemed the corrupt making-creatures, men, in a way fitting to this aspect, as to others, of their strange nature. The Gospels contain a fairy-story, or a story of a larger kind which embraces all the essence of fairy-stories. They contain many marvels – particularly artistic, beautiful, and moving: 'mythical' in their perfect, self-contained significance; and at the same time powerfully symbolic and allegorical; and among the marvels is the greatest and most complete conceivable eucatastrophe. The Birth of Christ is the eucatastrophe of Man's history. The Resurrection is the eucatastrophe of the story of the Incarnation. This story begins and ends in joy. It has pre-eminently the 'inner consistency of reality'. There is no tale ever told that men would rather find was true, and none which so many skeptical men have accepted as true on its own merits. For the Art of it has the supremely convincing tone of Primary Art, that is, of Creation. To reject it leads either to madness or to wrath.
It is not difficult to imagine the peculiar excitement and joy that one would feel, if any specially beautiful fairy-story were found to be 'primarily' true, its narrative to be history, without thereby necessarily losing the mythical or allegorical significance that it had possessed. It is not difficult, for one is not called upon to try and conceive anything of a quality unknown. The joy would have exactly the same quality, if not the same degree, as the joy which the 'turn' in a fairy-story gives: such joy has the very taste of primary truth. (Otherwise its name would not be joy.) It looks forward (or backward: the direction in this regard is unimportant) to the Great Eucatastrophe). The Christian joy, the Gloria, is of the same kind; but it is pre-eminently (infinitely, if our capacity were not finite) high and joyous. Because this story is supreme; and it is true. Art has been verified. God is the Lord, of angels, and of men – and of elves. Legend and History have met and fused.
But in God's kingdom the presence of the greatest does not depress the small. Redeemed Man is still man. Story, fantasy, still go on, and should go on. The Evangelium has not abrogated legends; it has hallowed them, especially the 'happy' ending'. The Christian has still to work, with mind as well as body, to suffer, hope, and die; but he may now perceive that his bents and faculties have a purpose, which can be redeemed. So great is the bounty with which he has been treated that he may now, perhaps, fairly dare to guess that in Fantasy he may actually assist in the effoliation and multiple enrichment of creation. All tales may come true; and yet, at the last, redeemed, they may be as like and as unlike the forms that we give them as Man, finally redeemed, will be like and unlike the fallen that we know.
--J.R.R. Tolkien, On Fairy Stories