Aristotle contended that "He who is by nature not his own but another's and yet a man, is by nature a slave; and he may be said to belong to another who being a human being is also a possession" ( Politics, 1, 6). This defines slavery in its simplest form, but in Roman times there were degrees of slavery ranging from that of mere chattel to that of colonus or adscripticius, i.e., one bound to the soil who yet might have land and possessions of his own. Owing to the influence of Stoicism, Christian ethics, shortage of the slave supply, burden of taxation, exhaustion of the soil, and economic inefficiency, slavery from the time of the Gracchi declined. By the time of the barbarian invasions it had almost disappeared and its place had been taken by the colonate, an attempted panacea for the rural exodus to the cities. When the coloni, who were legally free men, were bound to the soil throughout the Roman Empire, the foundations of medieval villeinage were laid. From the selections quoted here, which show a Christian influence at work on the law, we can judge how harshly the slaves were treated in the days of the Republic and the early Empire.
Source: The Institutes of Justinian, translated by Thomas Cooper, pp. 11-12 ( J. S. Voorhies, New York, 1852). -- A.D. 5 33).
Slavery is when one man is subjected to the dominion of another according to the law of nations but contrary to natural right.
Slaves are denominated servi from the practice of our generals