Protagoras was supposedly discovered as a porter who tied firewood with perfect geometry
Legend says the philosopher Democritus spotted a young porter in Abdera whose bundle of sticks was bound with such precise geometry that he must be a genius, and took him in. That porter became Protagoras, the first professional Sophist and author of the famous claim that man is the measure of all things.
Born around 490 BC in Abdera in Thrace, across from the island of Thasos, Protagoras became well known in Athens and a friend of Pericles. Plutarch tells of the two spending an entire day on a single puzzle: when an athlete was accidentally killed by a javelin at the games, who was responsible, the javelin, the thrower or the officials running the contest? Plato credits him with inventing the very role of the paid Sophist, and in Plato's dialogue named after him he promises to teach people to manage their households well and to contribute effectively to the life of the city.
His best-known sentence opened a book called Truth. Plato read it as a denial that objective truth exists. Protagoras seems rather to have meant that each person's judgments of good, bad, beautiful or unjust grow out of their own lifetime of experience, so people will naturally disagree. He knew the idea was provocative and counterintuitive, and argued that taking other people's views seriously, even when they clash with ours, is what allows a community to settle its affairs through open democratic debate.
Despite his mentor, he had little love for mathematics. Aristotle records him attacking geometers on the grounds that no real object is perfectly straight or curved, and no ruler actually touches a circle at a single point. Philodemus has him calling the subject unknowable and its jargon distasteful. On skill in general he held that theory without practice, and practice without theory, amount to nothing.
He cared about language too. He analysed a poem by Simonides for its wording and its author's intent, a skill useful for reading laws in Athenian courts. Diogenes Laërtius says he classified types of speech such as assertion, question, answer and command, and Aristotle credits him with work on grammatical gender. According to Plato's Meno he died at about 70 after forty years as a Sophist, probably around 420 BC, though stories of an impiety trial appear to be invented.
Source: Protagoras
