ty to that of freedom, and taught philosophers to substantiate
their theories by reason and by fact. There is no better illustration
of his painstaking investigation than his writing 250 constitutional
histories as the foundation of his work on "Politics." In this
masterly work will be found an exposition of political theories and
practice worthy the attention of all modern political philosophers.
The service given by Aristotle to the learning of the Middle Ages, and,
in fact, to modern philosophy, was very great.

Aristotle was of a more practical turn of mind than Plato. While he
introduced the formal syllogism in logic, he also introduced the
inductive method. Perhaps Aristotle represented the wisest and most
learned of the Greeks, because he advanced beyond the speculative
philosophy to a point where he attempted to substantiate theory by
facts, and thus laid the foundation for comparative study.

_Other Schools_.--The Epicureans taught a philosophy based upon
pleasure-seeking--or, as it may be stated, making happiness the highest
aim of life. They said that to seek happiness was to seek the highest
good. This philosophy in its pure state had no evil ethical tendency,
but under the bad influences of remote followers of Epicurus it led to
the degeneration of ethical practice. "Beware of excesses," says
Epicurus, "for they will lead to unhappiness." Beware of folly and
sin, for they lead to wretchedness. Nothing could have been better
than this, until people began to follow sensuality as the immediate
return of efforts to secure happiness. Then it led to {225}
corruption, and was one of the causes of the downfall of Greek as well
as the Roman civilization.

The Stoics were a group of philosophers who placed great emphasis upon
ethics in comparison with logic and physics. They looked on the world
from the pessimistic side and made themselves happy by becoming
martyrs. They taught that suffering, the endurance of pain without
complaint, was the highest virtue. To them logic was the science of
thought and of expression, physics was the science of nature, and
ethics the science of the good. All ideas originated from sensation,
and perception was the only criterion of truth. "We know only what we
perceive (by sense); only those ideas contain certain knowledge for us
which are ideas of real objects." The soul of man was corporeal and
material, hence physics and metaphysics were almost identical. There
is