Noah about to be baptised. In medieval Christianity, Noah's three sons were generally considered as the founders of the populations of the three known continents, Japheth/Europe, Shem/Asia, and Ham/Africa, although a rarer variation held that they represented the three classes of medieval society – the priests (Shem), the warriors (Japheth), and the peasants (Ham). In medieval Christian thought, Ham was considered to be the ancestor of the people of black Africa. So, in racialist arguments, the curse of Ham became a justification for the slavery of the black races. Isaac Newton, in his religious works on the development of religion, wrote
Ennoblement personal virtue: Shem, Ham and Japheth sprang from the same father, yet Ham was ignoble and King David rose from shepherd to become king through sheer faith and soldierly courage. Bartolus defined natural nobility by reference to Aristotle, who in his "Politics" explains how some are marked out for freedom by their virtues (and specifically by their capacity to rule), and are so distinguished from the mass of men whose talents fit them only for a servile role. Those free men whose virtues thus fit them to rule Bartolus defines as the natural nobility. With regard to natural nobility, Bartolus