Which C.S. Lewis book examines medieval and Renaissance ideas of the universe?

The Discarded Image examines medieval and Renaissance ideas of the universe.

Published in 1964, The Discarded Image: An Introduction to Medieval and Renaissance Literature was Lewis’s final completed book. It explains the model of the cosmos that shaped much premodern literature, including ideas about Earth, the planets, the fixed stars, angels, and the relationship between the physical and spiritual realms.

Lewis wrote the book as a literary scholar rather than as a novelist. He shows how understanding older cosmology helps modern readers interpret works from the Middle Ages and Renaissance. The title refers to the older intellectual picture of the universe that modern science largely displaced.

The book is not primarily a work of astronomy, and it does not argue that medieval cosmology is scientifically correct. Its purpose is historical and literary: to explain the imaginative framework behind texts written before modern scientific models became dominant.