What was the title of C.S. Lewis's 1956 autobiographical book about conversion and faith?

C.S. Lewis's 1956 autobiographical book about conversion and faith is Surprised by Joy.

Surprised by Joy: The Shape of My Early Life recounts Lewis’s childhood, education, intellectual development and movement from atheism toward Christianity. It was published in 1955 in the United Kingdom and in 1956 in the United States; the date 1956 is commonly associated with the American edition.

The title refers to “joy,” Lewis’s term for a profound, fleeting longing awakened by experiences such as reading myth and poetry. He distinguished this feeling from ordinary happiness and treated it as an important thread in his spiritual development.

The book is sometimes confused with The Pilgrim’s Regress, Lewis’s 1933 allegorical novel, or Mere Christianity, which grew from wartime radio broadcasts. A Grief Observed is also autobiographical, but it concerns Lewis’s response to Joy Davidman’s death rather than his early conversion.