Aristotle

The city is a political partnership that comes into being for purposes of self-sufficiency but exists primarily for the sake of living well. Man is by nature a political animal, because he has the ability to communicate and to dialogue and about justice and the good. The city is prior to the individual.
Natural slaves are those who perceive reason but do not have it. It is mutually beneficial that such people be ruled. There are also slaves according to the law, who may or may not be natural slaves. Mastery is rule over slaves, but political rule is rule over free and equal persons.
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