Aristotle: A Treatise on Government

BOOK IV 5. CHAPTER V

Of the different species of oligarchies one is, when the right to the offices is regulated by a certain census; so that the poor, although the majority, have no share in it; while all those who are included therein take part in the management of public affairs. Another sort is, when [1292b] the magistrates are men of very small fortune, who upon any vacancy do themselves fill it up: and if they do this out of the community at large, the state approaches to an aristocracy; if out of any particular class of people, it will be an oligarchy. Another sort of oligarchy is, when the power is an hereditary nobility. The fourth is, when the power is in the same hands as the other, but not under the control of law; and this sort of oligarchy exactly corresponds to a tyranny in monarchies, and to that particular species of democracies which I last mentioned in treating of that state: this has the particular name of a dynasty. These are the different sorts of oligarchies and democracies.

It should also be known, that it often happens that a free state, where the supreme power is in the laws, may not be democratic, and yet in consequence of the established manners and customs of the people, may be governed as if it was; so, on the other hand, where the laws may countenance a more democratic form of government, these may make the state inclining to an oligarchy; and this chiefly happens when there has been any alteration in the government; for the people do not easily change, but love their own ancient customs; and it is by small degrees only that one thing takes place of another; so that the ancient laws will remain, while the power will be in the hands of those who have brought about a revolution in the state.