With all his originality, Heraclitus remains an Ionian. In a
sense, Heraclitus substituted fire for the 'air' of Anaximenes, who in
turn had substituted 'air' for the water of Thales. Also, Hereclitus'
notion of flux is a development of that Anaximenes' notion of
rarefaction and condensation. Although Hereclitus has a doctrine of the
soul, his fire-soul is as little personal as the breath-soul of
Anaximenes. Some fragments superficially appear to assert the
immortality of the individual soul. But, when we examine them, we see
they cannot bear this interpretation. Soul is only immortal in so far as
it is part of the everliving fire which is the life of the world. Seeing
that the soul of every man is in constant flux like his body, what
meaning can immortality have? It is not only true that we cannot step
twice into the same river, but also that we are not the same for two
successive instants. That is just the side of his doctrine that struck
contemporaries most forcibly, and Epicharmos already made fun of it by
putting it as an argument into the mouth of a debtor who did not wish to
pay. How could he be liable, seeing he is not the same man that
contracted the debt?
Excerpt from the Encyclopedia Britannica without permission.