This chapter considers Hume’s treatment of ways that people exercise power over one another as individual members of society or when civil authorities fail to preserve peace. “Of the Populousness of Ancient Nations” is central to understanding this treatment. The logic of this essay relies on a conception of human nature that involves both universal, static features and significant malleability in response to circumstance. Once we understand this, we can better understand Hume’s comparisons of war and slavery in the ancient and modern worlds. He believes that modern developments have curtailed our domineering tendencies in the realms of war and, ironically, slavery. Hume has an acute appreciation of the psychological principles that make slavery so cruel, including the complex workings of sympathy. Yet he all but ignores the emerging horror of modern colonial slavery and praises modern society for progress in overcoming this evil. The priesthood, however, is an institution whose domineering effects Hume believes to have increased over time.