In The Republic, Plato describes what he considers to be the ideal city Kallipolis (the influence of his exile to Sparta is evident, eg the exclusion of poets or bards or any kind of artist.) Among other things he divides the population into three classes: guardians (the rulers); auxiliaries (soldiers/police/defenders); and producers (workers). While there can be some movement between classes, a person is generally born to their class.

In general, I disagree with most of Plato’s ideas about Kallipolis, but one idea I think I’d like to see implemented is that the rulers can’t own any property, so they have to rely on the goodwill of the rest of the population for food and lodging — which in turn is dependent on the rulers’ good governance.