The Origin of the Distinction of Ranks is one of the major products of the Scottish Enlightenment and a masterpiece of jurisprudence and social theory. Drawing on Adam Smith’s four-stages theory of history and the natural law’s traditional division of domestic duties into those toward servants, children, and women, Millar provides a rich historical analysis of the ways in which progressive economic change transforms the nature of authority. In particular he argues that, with the progress of arts and manufacture, authority tends to become less violent and concentrated, and ranks tend to diversify. Millar’s discussion of servitude is possibly the most well-developed of the economic arguments against slavery. John Millar (1735–1801) attended Adam Smith’s lectures at the University of Glasgow and later became a distinguished professor of law there.