The economy and culture of Ancient Greece and Rome (the Roman Republic and the Roman Empire) was fundamentally dependent on slave labor.
Despite its pretensions of being a bastion of liberty, rational philosophy, and democracy, Ancient Athens had the largest slave population in the Balkans and the Levant. Most historians accept that there were at least 80,000 slaves in Ancient Athens when it was at the peak of power (out of a population of 120,000). But the actual number of slaves might be higher than this. In the census ordered by tyrant Demetrius Phalereus, between 317 and 307 BC, it was found that the population of Attica consisted of 21,000 citizens, 10,000 metics and 400,000 slaves—this means that the number of slaves was twenty times more than the free citizens. Prostitution flourished in Ancient Athens and was dominated by the slave women and men captured in wars.
Slavery was regarded as a natural and necessary condition in the city-states of Ancient Greece. Aristotle held the view that slavery was necessary for philosophical life. On an average, the households of Athens had four to five slaves. Almost all Athenian citizens owned at least one slave. Not owning even one slave was a clear sign of extreme poverty. Aristotle defines a household as a house that contains freemen and slaves. Socrates has talked against the institution of slavery but his two wives—Xanthippe and Myrto—probably owned several slaves.
Ancient Rome took the institution of slavery to a new level. The purpose of the Roman Army was to conquer new territories and capture new slaves. Wherever the Roman Army went, a large contingent of Roman slave traders followed. The soldiers would catch people, immobilize them by tying them up or clubbing them on the head, and then sell them on the spot to the slave traders, who would transport the slaves to the slave markets which flourished on the trade routes running through the Roman territories. A significant part of the operational cost of the Roman Army was being recovered from the sale of slaves. In the time of the Roman Republic, the unskilled slaves used to cost at least 2000 sesterces (two years of the Roman version of minimum wage), and a skilled slave would cost much more.
The irony is that the Romans killed and enslaved a massive number of Greeks (a people whose philosophy and culture they admired) in the period when they conquered Greece. In the Battle of Corinth of 146 BC, the Roman general Lucius Mummius set fire to the city, slaughtered all the men, and enslaved all the women and children. After the barbaric destruction of Corinth, the rest of Greece was quickly subjugated by the Romans.
The number of slaves that the Roman soldiers caught and sold is astounding. The Samnite War in the third century BC resulted in 55,000 Samnites and Gauls being captured and auctioned in the slave markets. The destruction of Carthage in the third Punic War flooded the slave markets with more than a million slaves. Julius Caesar once sold the entire population of a conquered region (close to 53000 people) to slave dealers on the spot. Under Roman law, the slaves had no rights—their body was owned by their master. Sexual exploitation and torture of slaves was a common practice in Rome. The use of former enemy soldiers as slaves led to armed rebellions—like the one led by Spartacus. Close to 70,000 slaves participated in Spartacus’s rebellion.
In his book Ancient Slavery and Modern Ideology, Professor Moses Finley argues that there have been only five genuinely slave societies in history: Ancient Greece, Rome, the American South, the Colonial Caribbean and Brazil. All five were the key centers of Western power in the age when they were making massive use of slave labor. By genuinely slave societies, Finley means the societies which use a disproportionately high number of slaves, where the economy is heavily dependent on slave labor, and where the elites have developed cultural and political arguments for defending their use of slave labor. The slavery in Ancient Greece and Rome was not based on ethnicity, but the slavery in American South and the Colonial Caribbean and Brazil was.
There can be serious counterarguments to Finley’s points. In most civilizations, going back to the earliest Mesopotamian civilization, slavery was prevalent. The Egyptians, the Chinese, the Mongols, the South Americans, the Persians, the Islamic states, and many other cultures have made use of slave labor. But these civilizations were not as dependent on slave labor as Ancient Greece and Rome, and the colonial territories in North and South America. Consider the fact that between the fifteenth and the nineteenth centuries, the British, Dutch, French, Portuguese and Spanish brought millions of slaves from Africa and other regions to their colonies in North and South Americas. They totally transformed the ethnic makeup of these lands.