Diogenes Laertius Vitae philosophorum 3.1.82

[82] There are five forms of civil government: one form is democratic, another aristocratic, a third oligarchic, a fourth monarchic, a fifth that of a tyrant. The democratic form is that in which the people has control and chooses at its own pleasure both magistrates and laws. The aristocratic form is that in which the rulers are neither the rich nor the poor nor the nobles, but the state is under the guidance of the best. Oligarchy is that form in which there is a property-qualification for the holding of office; for the rich are fewer than the poor. Monarchy is either regulated by law or hereditary. At Carthage the kingship is regulated by law, the office being put up for sale. ¹