C.S. Lewis examines four types of love in The Four Loves.
The 1960 book discusses affection, friendship, erotic love, and charity. Lewis uses Greek terms to distinguish them: storge for affection, philia for friendship, eros for romantic or sexual love, and agape for self-giving love, which he links with Christian charity.
The work developed from a series of BBC radio talks broadcast in 1958. Lewis explores how each form can be valuable while also becoming distorted when treated as an absolute. His discussion combines classical language, Christian theology, literary examples, and observations about ordinary relationships.
The title does not mean that every human relationship fits neatly into only one category. Lewis presents the four loves as overlapping patterns and stresses that natural loves require a larger framework of charity. The book is therefore more an analysis of kinds and conditions of love than a simple numbered list.