The Complete Aristotle (eng.)

common people, transgresses the mean
and predominates, draws the constitution its own way, and thus
arises either oligarchy or democracy. There is another reason—the
poor and the rich quarrel with one another, and whichever side gets
the better, instead of establishing a just or popular government,
regards political supremacy as the prize of victory, and the one
party sets up a democracy and the other an oligarchy. Further, both
the parties which had the supremacy in Hellas looked only to the
interest of their own form of government, and established in
states, the one, democracies, and the other, oligarchies; they
thought of their own advantage, of the public not at all. For these
reasons the middle form of government has rarely, if ever, existed,
and among a very few only. One man alone of all who ever ruled in
Hellas was induced to give this middle constitution to states. But
it has now become a habit among the citizens of states, not even to
care about equality; all men are seeking for dominion, or, if
conquered, are willing to submit.
    What then is the best form of government, and what makes it the
best, is evident; and of other constitutions, since we say that
there are many kinds of democracy and many of oligarchy, it is not
difficult to see which has the first and which the second or any
other place in the order of excellence, now that we have determined
which is the best. For that which is nearest to the best must of
necessity be better, and that which is furthest from it worse, if
we are judging absolutely and not relatively to given conditions: I
say ‘relatively to given conditions,’ since a particular government
may be preferable, but another form may be better for some
people.
XII
    We have now to consider what and what kind of government is
suitable to what and what kind of men. I may begin by assuming, as
a general principle common to all governments, that the portion of
the state which desires the permanence of the constitution ought to
be stronger than that which desires the reverse. Now every city is
composed of quality and quantity. By quality I mean freedom,
wealth, education, good birth, and by quantity, superiority of
numbers. Quality may exist in one of the classes which make up the
state, and quantity in the other. For example, the meanly-born may
be more in number than the well-born, or the poor than the rich,
yet they may not so much exceed in quantity as they fall short in
quality; and therefore there must be a comparison of quantity and
quality. Where the number of the poor is more than proportioned to
the wealth of the rich, there will naturally be a democracy,
varying in form with the sort of people who compose it in each
case. If, for example, the husbandmen exceed in number, the first
form of democracy will then arise; if the artisans and laboring
class, the last; and so with the intermediate forms. But where the
rich and the notables exceed in quality more than they fall short
in quantity, there oligarchy arises, similarly assuming various
forms according to the kind of superiority possessed by the
oligarchs.
    The legislator should always include the middle class in his
government; if he makes his laws oligarchical, to the middle class
let him look; if he makes them democratical, he should equally by
his laws try to attach this class to the state. There only can the
government ever be stable where the middle class exceeds one or
both of the others, and in that case there will be no fear that the
rich will unite with the poor against the rulers. For neither of
them will ever be willing to serve the other, and if they look for
some form of government more suitable to both, they will find none
better than this, for the rich and the poor will never consent to
rule in turn, because they mistrust one another. The arbiter is
always the one trusted, and he who is in the middle is an arbiter.
The more perfect the admixture of the political elements, the more
lasting will be the constitution. Many even of those who desire to
form aristocratical governments make a mistake, not only in giving
too much power to the rich, but in attempting to overreach the
people. There comes a time when out of a false good there arises a
true evil, since the encroachments of the rich are more destructive
to the constitution than those of the people.
XIII
    The devices by which oligarchies deceive the people are five in
number; they relate to (1) the assembly; (2) the magistracies; (3)
the courts of law; (4) the