Protagoras asserted that there were two sides to every question, exactly opposite to each other.
The more I read about him, the less I wonder that they poisoned him. If he had treated me as he is said to have treated Protagoras, Hippias, and Gorgias, I could never have forgiven him.
Skepticism with regard to the senses had troubled Greek philosophers from a very early stage... The Sophists , notably Protagoras and Gorgias , had been led by the ambiguities and apparent contradictions of sense-perception to a subjectivism not unlike Hume's.