It is impossible to say how many slaves there were in Greek city-states 2,500 years ago, at the time of Plato and Aristotle. One estimate is that in the peninsula of Attica, which includes Athens, there were in the fifth century BC around 100,000 slaves, perhaps a quarter of the population (Andrewes, 1971). In Sparta, free men were greatly outnumbered by the helots, who were a particular type of slave.
