These men were the Sophists,--rhetorical men, who taught the children of the rich; worldly men, who sought honor and power; frivolous men, trifling with philosophical ideas; sceptical men, denying all certainty in truth; men who as teachers added nothing to the realm of science, but who yet established certain dialectical rules useful to later philosophers. They were a wealthy, powerful, honored class, not much esteemed by men of thought, but sought out as very successful teachers of rhetoric, and also generally selected as ambassadors on difficult missions. They were full of logical tricks, and contrived to throw ridicule upon profound inquiries. They taught also mathematics, astronomy, philology, and natural history with success. They were polished men of society; not profound nor religious, but very brilliant as talkers, and very ready in wit and sophistry. And some of them were men of great learning and talent, like Democritus, Leucippus, and Gorgias. They were not pretenders and quacks; they were sceptics who denied subjective truths, and labored for outward advantage. They taught the art of disputation, and sought systematic methods of proof. They thus prepared the way for a more perfect philosophy than that taught by the Ionians, the Pythagoreans, or the Eleatics, since they showed the vagueness of such inquiries, conjectural rather than scientific. They had no doctrines in common. They were the barristers of their age, _paid_ to make the "worse appear the better reason;" yet not teachers of immorality any more than the lawyers of our day,--men of talents, the intellectual leaders of society. If they did not advance positive truths, they were useful in the method they created. They had no hostility to truth, as such; they only doubted whether it could be reached in the realm of psychological inquiries, and sought to apply knowledge to their own purposes, or rather to distort it in order to gain a case. They are not a class of men whom I admire, as I do the old sages they ridiculed, but they were not without their use in the development of philosophy. The Sophists also rendered a service to literature by giving definiteness to language, and creating style in prose writing. Protagoras investigated the principles of accurate composition; Prodicus busied himself with inquiries into the significance of words; Gorgias, like Voltaire, gloried in a captivating style, and gave symmetry to the structure of sentences.