For [that fairy-story essay] I coined the word ‘eucatastrophe’: the sudden happy turn in a story which pierces you with a joy that brings tears (which I argued it is the highest function of fairy-stories to produce). And I was there led to the view that it produces its peculiar effect because it is a sudden glimpse of Truth, your whole nature chained in material cause and effect, the chain of death, feels a sudden relief as if a major limb out of joint had suddenly snapped back. It perceives — if the story has literary ‘truth’ on the second plane (for which see the essay) — that this is indeed how things really do work in the Great World for which our nature is made. And I concluded by saying that the Resurrection was the greatest ‘eucatastrophe’ possible in the greatest Fairy Story — and produces that essential emotion: Christian joy which produces tears because it is qualitatively so like sorrow, because it comes from those places where Joy and Sorrow are at one, reconciled, as selfishness and altruism are lost in Love. Of course I do not mean that the Gospels tell what is only a fairy-story; but I do mean very strongly that they do tell a fairy-story: the greatest. Man the story-teller would have to be redeemed in a manner consonant with his nature: by a moving story. But since the author of it is the supreme Artist and the Author of Reality, this one was also made to Be, to be true on the Primary Plane. So that in the Primary Miracle (the Resurrection) and the lesser Christian miracles too though less, you have not only that sudden glimpse of the truth behind the apparent Anankê of our world, but a glimpse that is actually a ray of light through the very chinks of the universe about us. I was riding along on a bicycle one day, not so long ago, past the Radcliffe Infirmary, when I had one of those sudden clarities which sometimes come in dreams (even anaesthetic-produced ones). I remember saying aloud with absolute conviction: ‘But of course! Of course that’s how things really do work’. But I could not reproduce any argument that had led to this, though the sensation was the same as having been convinced by reason (if without reasoning). And I have since thought that one of the reasons why one can’t recapture the wonderful argument or secret when one wakes up is simply because there was not one: but there was (often maybe) a direct appreciation by the mind (sc. reason) but without the chain of argument we know in our time-serial life. However that’s as may be.
— 7–8 November 1944, pp. 100–101 of The Letters of J.R.R. Tolkien