Such is the mild and conciliatory mode of treatment at first adopted by Plato in dealing with the principal representative of the Sophists—Protagoras. In the Dialogue which bears his name the famous humanist is presented to us as a professor of popular unsystematised morality, proving by a variety of practical arguments and ingenious illustrations that virtue can be taught, and that the preservation of social order depends upon the possibility of teaching it; but unwilling to go along with the reasonings by which Socrates shows the applicability of rigorously scientific principles to conduct. Plato has here taken up one side of the Socratic ethics, and developed it into a complete and self-consistent theory. The doctrine inculcated is that form of utilitarianism to which Mr. Sidgwick has given the name of egoistic hedonism. We are brought to admit that virtue is one because the various virtues reduce themselves in the last analysis to prudence. It is assumed that happiness, in the sense of pleasure and the absence of pain, is the sole end of life. Duty is identified with interest. Morality is a calculus for computing quantities of pleasure and pain, and all virtuous action is a means for securing a maximum of the one together with a minimum of the other. Ethical science is constituted; it can be taught like mathematics; and so far the Sophists are right, but they have arrived at the truth by a purely empirical process; while Socrates, who professes to know nothing, by simply following the dialectic impulse strikes out a generalisation which at once confirms and explains their position; yet from self-sufficiency or prejudice they refuse to agree with him in taking their stand on its only logical foundation. That Plato put forward the ethical theory of the Protagoras in perfect good faith cannot, we think, be doubted; although in other writings he has repudiated hedonism with contemptuous aversion; and it seems equally evident that this was his earliest contribution to positive thought. Of all his theories it is the simplest and most Socratic; for Socrates, in endeavouring to reclaim the foolish or vicious, often spoke as if self-interest was the paramount principle of human nature; although, had his assumption been formulated as an abstract proposition, he too might have shrunk from it with something of the uneasiness attributed to Protagoras. And from internal evidence of another description we have reason to think that the Dialogue in question is a comparatively juvenile production, remembering always that the period of youth was much more protracted among the Greeks than among ourselves. One almost seems to recognise the hand of a boy just out of college, who delights in drawing caricatures of his teachers; and who, while he looks down on classical scholarship in comparison with more living and practical topics, is not sorry to show that he can discuss a difficult passage from Simonides better than the professors themselves. III.