Plato is not speaking of Heracleitus, but of the Heracliteans, who
succeeded him; nor of the great original ideas of the master, but of the
Eristic into which they had degenerated a hundred years later. There is
nothing in the fragments of Heracleitus which at all justifies Plato's
account of him. His philosophy may be resolved into two elements--first,
change, secondly, law or measure pervading the change: these he saw
everywhere, and often expressed in strange mythological symbols. But he
has no analysis of sensible perception such as Plato attributes to him; nor
is there any reason to suppose that he pushed his philosophy into that
absolute negation in which Heracliteanism was sunk in the age of Plato. He
never said that 'change means every sort of change;' and he expressly
distinguished between 'the general and particular understanding.' Like a
poet, he surveyed the elements of mythology, nature, thought, which lay
before him, and sometimes by the light of genius he saw or seemed to see a
mysterious principle working behind them. But as has been the case with
other great philosophers, and with Plato and Aristotle themselves, what was
really permanent and original could not be understood by the next
generation, while a perverted logic carried out his chance expressions with
an illogical consistency. His simple and noble thoughts, like those of the
great Eleatic, soon degenerated into a mere strife of words. And when thus
reduced to mere words, they seem to have exercised a far wider influence in
the cities of Ionia (where the people 'were mad about them') than in the
life-time of Heracleitus--a phenomenon which, though at first sight
singular, is not without a parallel in the history of philosophy and
theology.

It is this perverted form of the Heraclitean philosophy which is supposed
to effect the final overthrow of Protagorean sensationalism. For if all
things are changing at every moment, in all sorts of ways, then there is
nothing fixed or defined at all, and therefore no sensible perception, nor