Which Tolkien academic essay introduced the influential idea of “eucatastrophe”?

J.R.R. Tolkien introduced the idea of “eucatastrophe” in his essay On Fairy-Stories.

Tolkien delivered the essay as the Andrew Lang lecture at the University of St Andrews in 1938, and it was published in revised form in 1947. In it, he argues that fairy-stories are not defined merely by small fairies or children’s entertainment. He discusses fantasy, recovery, escape, and consolation as important effects of the genre.

Tolkien uses “eucatastrophe” for a sudden joyful turn in a story, especially when hope appears at the point of greatest danger. He regarded it as an essential feature of the best fairy-stories. The term combines Greek elements associated with “good” and “catastrophe,” meaning a decisive change in events.

The essay connects this literary idea with Tolkien’s Christian beliefs and with his understanding of powerful narrative. Readers often identify the destruction of the Ring and the rescue at the Cracks of Doom as examples of eucatastrophic structure, although Tolkien’s essay is a theory of storytelling rather than a glossary for The Lord of the Rings.