Protagoras of Abdera, fl. 5th century BC. Greek philosopher, a contemporary of Socrates, numbered with Gorgias and others among the Older Sophists. He was exiled from Athens in 415 BC for impiety. No works of his have survived; we know of him through the writings of others, and especially through Plato's dialogue Protagoras, a rather unflattering portrait of him and his disciples in conversation with Socrates.
Essay asserting that Protagoras has been misconstrued as an individual (or absolute) relativist, and should be considered a "human relativist." www.geocities.com/inescapableennui/s12.html
Internet Encyclopedia of Philosophy article by Carol Poster. Deals extensively with what we know about the life, doctrines and influence of this Sophist. www.iep.utm.edu/p/protagor.htm