The Latin genesis of class nomenclature does not mean that the idea behind it (in either a social or general sense) did not exist prior to the rise of the Roman Republic. Aristotle's Organon proposed a logical system of classification of natural and linguistic types into genus and species according to categorical criteria. For the ancient Greeks, the Few and the Many constituted a central measure of division within the social order. Both Plato and Aristotle divided social groups into functional classes whose status and power was graded according to the contributions each made to the purposes of the civil community as a whole. Plato's Republic famously identified within the city three parts—rulers, soldiers, and laborers—while Aristotle distinguished six socioeconomic classes—soldiers, priests, judges, farmers, artisans, and traders—of whom only the first three were deemed fully qualified to exercise the rights associated with citizenship, at least in the best political system.
Class thus has generally been associated with systems of social exclusion. Indeed, elaborate mythologies have been generated to support or justify class divisions. The tale of Noah's curse on the descendents of his son Ham, in Genesis 9:20–27, has been taken as an explanation for class inequality. Likewise, the Koran (Sura 43:31) declares that social differentiation arises from Allah's will that the inferior should be subjected to the superior. The caste system that long governed social organization and relations in India and elsewhere in Asia purported to reflect the disparate origins of the various groups as described in the Vedas: the Brahmans from the lips of Brahma, the Kshatriya from the shoulders, the Vaisya from the thighs, and the Sudra from the feet.
During the European Middle Ages, the idea behind class distinctions was popularly captured by various forms of organic unities. Many medieval thinkers, quite possibly under the indirect influence of Plato, divided society into the threefold functional ordering of those who fight, those who work, and those who pray. In the High Middle Ages, this was gradually replaced by the more developed organic doctrine of the body politic, the most influential exponent of which was John of Salisbury (1115 or 1120–1180). His Policraticus (completed 1159) contained an extensive account of how each of the organs and limbs of the human body—from the head to the toes—had a direct counterpart in society, from the king, his advisors, soldiers, and diverse magistrates all the way down to the peasants and artisans. Class divisions were natural and necessary in order to maintain justice and the common good. Essentially this view enjoyed wide currency in Europe well into early modern times.