se who first tried to give some scientific account of the soul
or mind conceived it as a material thing, and that it was sufficiently
common to identify it with the breath, we know from direct evidence. A
glance at the Greek philosophy, to which we owe so much that is of
value in our intellectual life, is sufficient to disclose how difficult
it was for thinking men to attain to a higher conception.

Thus, Anaximenes of Miletus, who lived in the sixth century before
Christ, says that "our soul, which is air, rules us." A little later,
Heraclitus, a man much admired for the depth of his reflections,
maintains that the soul is a fiery vapor, evidently identifying it with
the warm breath of the living creature. In the fifth century, B.C.,
Anaxagoras, who accounts for the ordering of the elements into a system
of things by referring to the activity of Mind or Reason, calls mind
"the finest of things," and it seems clear that he did not conceive of
it as very different in nature from the other elements which enter into
the constitution of the world.

Democritus of Abdera (between 460 and 360 B.C.), that great
investigator of nature and brilliant writer, developed a materialistic
doctrine that admits the existence of nothing save atoms and empty
space. He conceived the soul to consist of fine, smooth, round atoms,
which are also atoms of fire. These atoms are distributed through the
whole body, but function differently in different places--in the brain
they give us thought, in the heart, anger, and in the liver, desire.
Life lasts just so long as we breathe in and breathe out such atoms.

The doctrine of Democritus was taken up by Epicurus, who founded his
school three hundred years before Christ--a school which lived and
prospered for a very long time. Those who are interested in seeing how
a materialistic psychology can be carried out in detail by an ingenious
mind should read the curious account of the mind presented in his great
poem, "On Nature," by the Roman poet Lucretius, an ardent Epicurean,
who wrote in the first century B.C.

The school which we commonly think of contrasting with the Epicurean,
and one which was founded at about the same time, is that of the
Stoics. Certainly the Stoics differed in many things from the
Epicureans; their view of the world, and of the life of man, was a much
nobler one; but they were uncompromising materialists, nevertheless,
and identified the soul with the warm breath that