Although Gorgias made major original contributions in the fields of philosophy and rhetoric, he is probably best known as the antagonist of Socrates' ideas in the Platonic dialogue titled Gorgias (circa 388 B.C.). He is indeed an appropriate, if outstanding, representative of the Sophists and rhetoricians of the ancient Greek world; and, in spite of the aura of disrepute often associated with those schools, much of Gorgias's thought appears strikingly modern, anticipating twentieth-century trends in literary theory and epistemology. His work that survives includes his speeches titled Praise of Helen and Defence of Palamedes. His book Concerning Nature or What is Not has been lost, but an account of it has been preserved by the second-century-A.D. writer Sextus Empiricus. As the philosopher and teacher known from both the fragmentary remains of his writings and his portrayal by Plato, Gorgias is significant for his provocative, skeptical challenges...