Which 1939 Tolkien lecture explained the value of fantasy and invented worlds?

The 1939 Tolkien lecture explaining the value of fantasy and invented worlds is “On Fairy-Stories.”

Tolkien originally delivered the talk as the Andrew Lang lecture at the University of St Andrews in Scotland on 8 March 1939. He later revised it for publication, and it became one of his best-known statements about fantasy, fairy stories, and imaginative creation.

The essay discusses concepts including sub-creation, recovery, escape, and consolation. Tolkien argued that fantasy can offer readers a renewed view of ordinary things, not merely an escape from reality. He also described the importance of a “secondary world” that has its own internal consistency.

The work is often read alongside Tolkien’s fiction because it explains ideas behind his method as a world-builder. It is not the same essay as “Beowulf: The Monsters and the Critics,” his major 1936 lecture on Old English poetry.