[edit] And don't get me started on Aristotle's politics, which in my view were largely self interested, shallow and myopic. For example -

"But is there any one thus intended by nature to be a slave, and for whom such a condition is expedient and right, or rather is not all slavery a violation of nature?

There is no difficulty in answering this question, on grounds both of reason and of fact. For that some should rule and others be ruled is a thing not only necessary, but expedient; from the hour of their birth, some are marked out for subjection, others for rule."

Now if we compare that to the story of Diogenes when he was taken and sold as a slave and then asked by the gangmaster what he was useful for, he apparently told them that he was quite useless at everything, other than as a governer of others. Also he apparently told Alexander the Great "I was searching through some bones for those of your father, but could not distinguish them from those of a slave."