Which C.S. Lewis book examines four types of love?

The Four Loves examines four types of love: affection, friendship, erotic love, and charity. C.S. Lewis developed the book from a 1958 BBC radio series, and it was published in book form in 1960.

Lewis uses Greek terms to distinguish the categories: storge for affection, philia for friendship, eros for romantic or sexual love, and agape for self-giving love. His discussion does not treat these forms as completely isolated; they can overlap and influence one another.

The book is often confused with a simple guide to romantic relationships. Its wider subject is the role of love in human life, including family bonds, companionship, desire, and Christian charity. Lewis also considers how natural loves can become possessive when detached from a larger moral framework.