J. R. R. Tolkien on "Eucatastrophe" and Christianity

“The “consolation” of fairy-tales has another aspect than the imaginative satisfaction of ancient desires. Far more important is the consolation of the Happy Ending. Almost I would venture to assert that all complete fairy-stories must have it…I will call it Eucatastrophe [literally, “good catastrophe”]. The eucatastrophic tale is the true form of fairy-tale, and its highest function. The consolation of fairy-stories, the joy of the happy ending, or more correctly of the good catastrophe, of the sudden joyous “turn” does not deny the existence of dycatastrophe, of sorrow and failure; the possibility of these is necessary to the joy of deliverance. It denies (in the face of much evidence, if you will), universal final defeat and in so far is evangelium, giving a fleeting glimpse of Joy, Joy beyond the walls of the world, poignant as grief…In such stories when the sudden “turn” comes we get a piercing glimpse of joy, and heart’s desire, that for a moment passes outside the frame, rends indeed the very web of story, and lets a gleam come through.

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...Probably every writer making a secondary world, a fantasy, every sub-creator, wishes in some measure to be a real maker, or hopes that he is drawing on reality: hopes that the peculiar quality of this secondary world (if not all the details) are derived from Reality…The peculiar quality of “joy” in successful Fantasy can thus be explained as a sudden glimpse of the underlying reality or truth.

The answer to this question [“is it true?”] that I gave at first was (quite rightly): “If you have built your little world well, yes: it is true in that world.” That is enough for the artist…But in the “eucatastrophe” we see in a brief vision that the answer may be greater – it may be a far-off gleam or echo of evangelium in the real world.”

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 - peculiarly artistic, beautiful, and moving: “mythical” in their perfect, self-contained significance; among the marvels is the greatest and most complete conceivable eucatastrophe. But this story has entered History and the primary world; the desire and aspiration of sub-creation has been raised to the fulfillment of Creation. 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...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. The joy which the “turn” in the fairy-story gives…has the very taste of primary truth…It looks forward 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. But this story is supreme, and it is true.”

-J. R. R. Tolkien, "On Fairy Stories"