The slave trade between Africa and North America took place during a time when unequal social relations were the norm throughout Europe. The enslavement of human beings came naturally to a people accustomed to living with mastery and servitude. The British aristocrats who made up the first plantation society in America were accustomed to thinking of their own lower classes as brutish, unruly, and fit only for manual labor. Africans, in the opinion of many, were naturally slaves, and very few voices were raised against slavery in the colonies.

Nevertheless, abolitionists were speaking and writing as early as the late seventeenth century. The most eloquent of them came from among religious leaders such as the Quakers in Pennsylvania and the Puritan judge Samuel Sewall in Massachusetts. These voices strengthened in the wake of the American Revolution. The abolitionists insisted on a literal interpretation of...