Prôtagoras of Abdêra: latter half of fifth century B.C.
He wrote a book called Truth or Refutatory Arguments or On Being; and one On the Gods. Various other titles are mentioned.
1. (From 'Truth' or Refutatory Arguments'). Of all things the measure is Man, of the things that are, that they are, and of the things that are not, that they are not.
2. (From 'On Being').
(Porphyry: 'Few of the writings of Plato's predecessors have survived, otherwise Plato perhaps would have been detected in further plagiarisms. fit any rate, in the place where I happened to have been reading in Protagoras book "On Being" the argument he uses against those who make Being One, I find that he uses the same refutatory terms. For I took the trouble to memorise the passage word for word').
(Titles)
8a. 'On Constitution.'
8b. 'On the Original Social Structure.'
8c. 'On Ambition.'
8d. 'On Virtues.'
8e. 'On Human Errors.'
8f. 'Exhortation.'
8g. 'Trial concerning a Fee.'
8h. 'On the Underworld.'