According to Berlin, “what distinguished societies with slaves was the fact that slaves were marginal to the central productive process;slavery was just one form of labor among many.”

In his important study on slavery, Many Thousands Gone, Historian Ira Berlin discusses the difference between "slave societies" and "societies with slaves." According to Berlin, "What distinguished societies with slaves was the fact that slaves were marginal to the central productive processes; slavery was just one form of labor among many." In contrast, Berlin notes, "In slave societies...slavery stood at the center of economic production, and the master-slave relationship provided the model for all social relations: husband and wife, parent and child, employer and employee..."