Two thousand years ago a slave was merely a piece of machinery. Nowadays a rich man invests his money in factories. The rich people of Rome (senators, generals and war-profiteers) invested theirs in land and in slaves. The land they bought or took in the newly-acquired provinces. The slaves they bought in open market wherever they happened to be cheapest. During most of the third and second centuries before Christ there was a plentiful supply, and as a result the landowners worked their slaves until they dropped dead in their tracks, when they bought new ones at the nearest bargain-counter of Corinthian or Carthaginian captives.