Book 8: Friendship or Love.
Chapter 10: Of the three forms of constitution.
Now, of constitutions there are three kinds, and an equal number of perverted forms, which are, so to speak, corruptions of these. Constitutions proper are kingly government and aristocracy; and, thirdly, there is a form of government based upon an assessment of property, which should strictly be called timocracy, though most people are wont to speak of it as constitutional government simply.
Of these, kingly government is the best and timocracy the worst. The perversion of kingly government is tyranny: both are monarchies, but there is a vast difference between them; for the tyrant seeks his own interest, the king seeks the interest of his subjects. For he is not properly a king who is not self-sufficient and superabundantly furnished with all that is good; such a man wants nothing more; his own advantage, then, will not be his aim, but that of his subjects. A man of another character than this could only be the sort of king that is chosen by lot.
Tyranny is the opposite of kingly rule, because the tyrant seeks his own good; and of this government it is quite obvious that it is the worst of all: we may add that the opposite of the best must be the worst.
Kingly government degenerates into tyranny; for tyranny is a vicious form of monarchy: the bad king, then, becomes a tyrant.
Aristocracy degenerates into oligarchy through the vice of the rulers, who, instead of distributing public property and honours according to merit, take all or most of the good things for themselves, and give the offices always to the same people, setting the greatest store by wealth; you have, then, a small number of bad men in power, in place of the best men.
Lastly, timocracy degenerates into democracy: and indeed they border closely upon each other; for even timocracy is intended to be government by the multitude, and all those who have the property qualification are equal.
Democracy is the least bad [of the corrupt forms], for it is but a slight departure from the corresponding form of constitution.
These, then, are the ways in which the several constitutions are most apt to change; for these are the directions in which the change is slightest, and encounters the least resistance.
Likenesses of these forms of government and patterns of them, so to speak, may be found in families. For instance, the association of father and sons has the form of kingly rule; for the father cares for his children. This, also, is the reason why Homer addresses Zeus as father; for kingly government aims at being a paternal government. But in Persia the association of father and son is tyrannical; for fathers there use their sons as slaves. The association of master and slave is also tyrannical; for it is the interest of the master that is secured by it. But this seems to be a legitimate kind of tyranny, while the Persian kind seems to be wrong; for different beings require different kinds of government.
The association of man and wife seems to be aristocratic: for the husband bears rule proportionate to his worth, i.e. he rules in those matters which are his province; but he entrusts to his wife those matters that properly belong to her. But when the man lords it in all things, he perverts this relation into an oligarchical one; for he then takes rule where he is not entitled to it, and not only in those matters in which he is better. Sometimes, on the other hand, the wife rules because she is an heiress. In these cases authority is not proportionate to merit, but is given on the ground of wealth and influence, just as in oligarchies.
The association of brothers resembles a timocracy; for they are equal except in so far as they differ in age. On this account, if they differ very widely in age, their friendship can no longer be a brotherly friendship.
A democratic form of association is chiefly found in those households which have no master (for there all are on a footing of equality), or where the head of the house is weak, and every one does what he likes.