What title did J.R.R. Tolkien give his 1939 lecture later published as an essay about fantasy?

J.R.R. Tolkien titled his 1939 lecture and later essay On Fairy-Stories.

Tolkien delivered the lecture as the Andrew Lang Lecture at the University of St Andrews in Scotland on 8 March 1939. He was invited to discuss fairy tales, but he used the occasion to present a broad account of fantasy, imaginative creation, and the value of traditional stories.

The essay argues that fairy stories are not merely childish entertainment. Tolkien describes important functions that he calls Recovery, Escape, and Consolation. He also discusses the creation of a secondary world, a fictional realm that can feel internally consistent and believable to its readers.

On Fairy-Stories was later published in expanded form in Essays Presented to Charles Williams in 1947. It is often read alongside Tolkien’s fiction because it explains principles visible in The Hobbit and The Lord of the Rings. The essay’s ideas helped shape modern discussions of fantasy literature.