希腊语前缀 eu-（好）＋ catastrophe（灾变——古典戏剧批评里指剧情最后的「解结」）。 把「好」焊在「灾变」前头，让一个词自己完成了那个急转。

Greek eu- (good) welded onto catastrophe — in classical criticism, the final “unravelling” of a drama’s plot. The word performs its own sudden turn.

托尔金在论文《论仙境奇谭》（1939 年首讲）里铸出它，宣布这是仙境故事的最高职能： 不是否认悲伤，而是在承认一切败局之后，给出「突然而至的、恩典一般的好转—— 从不担保再来」。1944 年他写给儿子克里斯托弗的信成了 OED 的最早书证。

最好的注脚是他自己的履历：托尔金战后第一份工作，就是 OED 的编纂助理。 几十年后，他造的词回到了老东家的词典里——词典人造的词，被词典收录， 和 petrichor、numinous 同属一个小传统：学者造词，转正入籍。

Tolkien struck the word in On Fairy-Stories (first delivered 1939), declaring it the highest function of the fairy tale: not to deny sorrow, but — with every defeat admitted — to deliver “a sudden and miraculous grace: never to be counted on to recur.” His 1944 letter to his son Christopher is the OED’s earliest evidence.

The best footnote is his own résumé: Tolkien’s first postwar job was as an assistant on the OED. Decades later, his coinage came home to his old employer’s pages — a dictionary man’s word, taken in by the dictionary — joining petrichor and numinous in that small tradition of scholars’ coinages gone legitimate.

「绝处逢生」「柳暗花明」都在现场，但都站在得救的人那一边； eucatastrophe 站在故事那一边——它是一种叙事学配件，讲的是「转」本身的机制与快感。 「反转」倒是叙事词，可惜情感是中性的：反转可以转坏，eucatastrophe 只往好里转， 而且要求转得让人鼻酸。

绝处逢生 and 柳暗花明 are both on the scene, but both stand with the rescued; eucatastrophe stands with the story — it is a piece of narrative machinery, about the mechanism and the pang of the turn itself. 反转 is properly narratological but emotionally neutral: a 反转 can turn either way, while a eucatastrophe turns only toward the good — and must turn hard enough to sting the eyes.