Which C.S. Lewis book recounts his spiritual autobiography?

Surprised by Joy is C.S. Lewis's spiritual autobiography.

Published in 1955, the book describes Lewis's intellectual and religious development, including his movement from childhood Christianity to atheism and eventually back to Christian belief. Lewis uses the idea of “joy” for a recurring experience of intense longing sparked by literature, mythology, nature, or imagination.

The autobiography is not a complete account of every part of Lewis's life. It concentrates on the formation of his ideas and faith, especially his education, reading, military service, and friendships. The title refers to the unexpected nature of the longing he came to regard as spiritually significant.

A Grief Observed is different: it records Lewis's response to the death of his wife, Joy Davidman. The Four Loves is an analysis of kinds of love, while Mere Christianity presents arguments and broadcasts about Christian belief. These works overlap in subject matter but are not his spiritual autobiography.