From time out of mind, people have killed, maimed, and oppressed one another in two sorts of conflicts: over material interests (real estate, slave labor, agricultural surplus, war booty, and so on) and over what Max Weber would have termed "ideal interests" (conflicts over ultimate meanings, salvation, principles of justice, definitions of social order). Barrington Moore's classical and landmark study, Social Origins of Democracy and Dictatorship: Lord and Peasant in the Making of the Modern World (1966), explored the first mode of conflict in the making of modern nation-states. All social scientists are forever in his debt for that effort. It ranks as one of the most important contributions to the fields of comparative and historical sociology.