C.S. Lewis discusses four loves in The Four Loves. He examines affection, friendship, eros, and charity, using both classical Greek terms and Christian reflection.
Affection, or storge, describes natural fondness, including the bonds that can grow within families. Friendship, or philia, concerns shared interests and companionship. Eros refers to romantic or sexual love, while charity, or agape, is self-giving love associated with Christian love.
The book developed from a series of BBC radio talks and was published in 1960. Lewis distinguishes the loves without treating them as sealed compartments: real relationships can involve more than one kind at the same time.
The Greek labels are sometimes presented differently in summaries, especially because English translations vary. The stable count is four, and the four English categories are affection, friendship, eros, and charity.