'Whether there are gods or not, I cannot tell.' Nor have we any other
trustworthy evidence of the tenets of Protagoras, or of the sense in which
his words are used. For later writers, including Aristotle in his
Metaphysics, have mixed up the Protagoras of Plato, as they have the
Socrates of Plato, with the real person.

Returning then to the Theaetetus, as the only possible source from which an
answer to these questions can be obtained, we may remark, that Plato had
'The Truth' of Protagoras before him, and frequently refers to the book.
He seems to say expressly, that in this work the doctrine of the
Heraclitean flux was not to be found; 'he told the real truth' (not in the
book, which is so entitled, but) 'privately to his disciples,'--words which
imply that the connexion between the doctrines of Protagoras and
Heracleitus was not generally recognized in Greece, but was really
discovered or invented by Plato. On the other hand, the doctrine that 'Man
is the measure of all things,' is expressly identified by Socrates with the
other statement, that 'What appears to each man is to him;' and a reference
is made to the books in which the statement occurs;--this Theaetetus, who
has 'often read the books,' is supposed to acknowledge (so Cratylus). And
Protagoras, in the speech attributed to him, never says that he has been
misunderstood: he rather seems to imply that the absoluteness of sensation
at each instant was to be found in his words. He is only indignant at the
'reductio ad absurdum' devised by Socrates for his 'homo mensura,' which
Theodorus also considers to be 'really too bad.'

The question may be raised, how far Plato in the Theaetetus could have
misrepresented Protagoras without violating the laws of dramatic
probability. Could he have pretended to cite from a well-known writing
what was not to be found there? But such a shadowy enquiry is not worth
pursuing further. We need only remember that in the criticism which