But at the story of the little boy (which is a fully attested fact of course) with its apparent sad ending and then its sudden unhoped-for happy ending, I was deeply moved and had that peculiar emotion we all have – though not often. […] For it 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).
Source: wiktionary
Let us hymn the small but journal wonders
of Nature and of households, and then finish
on a serio-comic note with legends
of ultimate eucatastrophe,
regeneration beyond the waters.
Source: wiktionary
The "problem" of T[homas] S[tearns] Eliot comes partly from our post-Christian sense of a world where Tolkien's eucatastrophes never happen, and partly from the way we write biography.
Source: wiktionary
Literary unity demands that once a eucatastrophe happens it must be accepted as part of the story rather than as an arbitrary whim of the author.
Source: wiktionary