The social structure of the Roman Empire has been described as a pyramid, with the very narrow tip being the wealthiest aristocracy, the middle part being the more prosperous upper class of the cities of the Empire, and the broadest part being the vast majority of inhabitants of the Empire who existed at subsistence level. The basic unit of the Roman society was the familia or household, which consisted not only of the members of an immediate family but also relatives living in the house, slaves and freed slaves. This stratification of the society affected her in all areas. Women of the imperial household were restricted to certain duties which were closed to lower class women, such as worship of certain gods or goddesses, membership of certain cults, and the privilege to be vestal virgins. As materfamilias, a woman was concerned with internal affairs, overseeing the social life and directing the education of children of both sexes.