From these considerations there will be no difficulty in seeing what should be the constitution of oligarchies. We have only to reason from opposites and compare each form of oligarchy with the corresponding form of democracy.
The first and best attempered of oligarchies is akin to a constitutional government. In this there ought to be two standards of qualification; the one high, the other low- the lower qualifying for the humbler yet indispensable offices and the higher for the superior ones. He who acquires the prescribed qualification should have the rights of citizenship. The number of those admitted should be such as will make the entire governing body stronger than those who are excluded, and the new citizen should be always taken out of the better class of the people. The principle, narrowed a little, gives another form of oligarchy; until at length we reach the most cliquish and tyrannical of them all, answering to the extreme democracy, which, being the worst, requires vigilance in proportion to its badness. For as healthy bodies and ships well provided with sailors may undergo many mishaps and survive them, whereas sickly constitutions and rotten ill-manned ships are ruined by the very least mistake, so do the worst forms of government require the greatest care. The populousness of democracies generally preserves them (for e state need not be much increased,since there is no necessity tha number is to democracy in the place of justice based on proportion); whereas the preservation of an oligarchy clearly depends on an opposite principle, viz., good order.
