In C.S. Lewis’s The Four Loves, philia names love based on friendship.
The Four Loves, published in 1960, examines four kinds of human affection using Greek terms. Lewis identifies storge with affection, philia with friendship, eros with romantic love, and agape, or charity, with self-giving love. The book grew from a series of BBC radio talks and later became one of Lewis’s most widely read works of popular theology.
Lewis treats philia as more than casual companionship. He presents friendship as a relationship formed when people recognize that they share an interest, outlook, or purpose. In the book’s famous image, friends stand side by side looking toward a common object rather than gazing only at one another.
The terms are not rigid scientific categories, and Lewis’s use of Greek vocabulary reflects a theological and literary interpretation rather than a complete account of ancient Greek usage. Philia is also sometimes translated broadly as affectionate love, but within The Four Loves the expected category is friendship.