On The Soul
simple, unmixed, and pure. He assigns both characteristics, knowing
and origination of movement, to the same principle, when he says
that it was mind that set the whole in movement.
Thales, too, to judge from what is recorded about him, seems to have
held soul to be a motive force, since he said that the magnet has a
soul in it because it moves the iron.
Diogenes (and others) held the soul to be air because he believed
air to be finest in grain and a first principle; therein lay the
grounds of the soul's powers of knowing and originating movement. As
the primordial principle from which all other things are derived, it
is cognitive; as finest in grain, it has the power to originate
Heraclitus too says that the first principle-the 'warm exhalation'
of which, according to him, everything else is composed-is soul;
further, that this exhalation is most incorporeal and in ceaseless
flux; that what is in movement requires that what knows it should be
in movement; and that all that is has its being essentially in
movement (herein agreeing with the majority).
Alcmaeon also seems to have held a similar view about soul; he
says that it is immortal because it resembles 'the immortals,' and
that this immortality belongs to it in virtue of its ceaseless
movement; for all the 'things divine,' moon, sun, the planets, and the
whole heavens, are in perpetual movement.
of More superficial writers, some, e.g. Hippo, have pronounced it to
be water; they seem to have argued from the fact that the seed of
all animals is fluid, for Hippo tries to refute those who say that the
soul is blood, on the ground that the seed, which is the primordial
soul, is not blood.
Another group (Critias, for example) did hold it to be blood; they
take perception to be the most characteristic attribute of soul, and
hold that perceptiveness is due to the nature of blood.
Each of the elements has thus found its partisan, except earth-earth