Philia is the name C.S. Lewis used for the friendship love celebrated in The Four Loves.
In The Four Loves, Lewis discusses four Greek terms used to distinguish kinds of love: affection, friendship, erotic love, and charity. Philia is the Greek term for friendship, especially the bond between companions who share interests, experiences, or a common pursuit.
Lewis describes friendship as a relationship that often grows when people recognize that they share a concern or vision. He contrasts it with eros, associated with romantic or sexual love; storge, associated with natural affection; and agape, associated with charitable or self-giving love.
The book began as a series of BBC radio talks and was published in 1960. “Philia” is sometimes confused with “agape” because both can describe non-romantic relationships, but Lewis treats them as distinct categories. His discussion draws on Greek vocabulary while developing a Christian philosophical interpretation.