Friendship, Altruism, and Morality, originally published in 1980, gives an account of "altruistic emotions" (compassion, sympathy, concern) and friendship that brings out their moral value. Blum argues that moral theories centered on rationality, universal principle, obligation, and impersonality cannot capture this moral importance. This was one of the first books in contemporary moral philosophy to emphasize the moral significance of emotions, to deal with friendship as a moral phenomenon, and to challenge the rationalism of standard interpretations of Kant, although Blum’s "sentimentalism" owes more to Schopenhauer than to Hume. It was a forerunner to care ethics, and feminist ethics more generally; to virtue ethics; and to subsequent influential interpretations of Kant that attempted to room for altruistic emotion and friendship, and other forms of particularism and partialism. In addition, the work has been widely influential in religious studies, political theory, bioethics, and feminist ethics.