Keen identifies five stages of loving — child, rebel, adult, outlaw, and lover — as a developmental framework for understanding how a man's relationship to himself, others, and the world transforms over a lifetime. This is one of the first serious attempts to map the stages of a man's loving life with the same depth that developmental psychology had given to cognitive and moral development. Keen draws on psychology, mythology, and philosophy to show that love is not a fixed capacity but a skill that grows through the willingness to be wounded, broken open, and transformed. Decades after its publication, it remains one of the most honest and philosophically grounded treatments of love as a masculine practice.