the struggle between classes. Democracy, he explains, is the
government not of the many but of the poor; oligarchy a government not
of the few but of the rich. And each class is thought of, not as
trying to express an ideal, but as struggling to acquire power or
maintain its position. If ever the class existed in unredeemed
nakedness, it was in the Greek cities of the fourth century, and its
existence is abundantly recognised by Aristotle. His account of the
causes of revolutions in Book V. shows how far were the existing
states of Greece from the ideal with which he starts. His analysis of
the facts forces him to look upon them as the scene of struggling
factions. The causes of revolutions are not described as primarily
changes in the conception of the common good, but changes in the
military or economic power of the several classes in the state. The
aim which he sets before oligarchs or democracies is not the good
life, but simple stability or permanence of the existing constitution.

With this spirit of realism which pervades Books IV., V., and VI. the
idealism of Books I., II., VII., and VIII. is never reconciled.
Aristotle is content to call existing constitutions perversions of the
true form. But we cannot read the Politics without recognising and
profiting from the insight into the nature of the state which is
revealed throughout. Aristotle's failure does not lie in this, that he
is both idealist and realist, but that he keeps these two tendencies
too far apart. He thinks too much of his ideal state, as something to
be reached once for all by knowledge, as a fixed type to which actual
states approximate or from which they are perversions. But if we are
to think of actual politics as intelligible in the light of the ideal,
we must think of that ideal as progressively revealed in history, not
as something to be discovered by turning our back on experience and
having recourse to abstract reasoning. If we stretch forward from what