Which C.S. Lewis book was published posthumously in 1964 as a study of medieval imagery?

The Discarded Image was published posthumously in 1964 as a study of medieval imagery.

The Discarded Image: An Introduction to Medieval and Renaissance Literature presents Lewis’s account of the medieval model of the universe and the imaginative system behind much medieval writing. The book was published after his death, in 1964, and grew from his long experience teaching medieval and Renaissance literature.

Lewis explains ideas such as the medieval picture of a structured cosmos, the relationship between the earthly and celestial realms, and the influence of classical sources on Christian medieval thought. His purpose was not simply to catalogue old beliefs but to show how an entire mental picture shaped literature, metaphor, and intellectual life.

The title refers to the replacement of that medieval model by newer scientific and philosophical pictures of reality. The work is an academic introduction, not a novel and not a personal memoir. It is especially useful for readers studying writers such as Chaucer, Dante, and Spenser, whose works assume cultural knowledge that modern readers may not share.