All the interests and contrasts of character in a great dramatic work like the Protagoras are not easily exhausted. The impressiveness of the scene should not be lost upon us, or the gradual substitution of Socrates in the second part for Protagoras in the first. The characters to whom we are introduced at the beginning of the Dialogue all play a part more or less conspicuous towards the end. There is Alcibiades, who is compelled by the necessity of his nature to be a partisan, lending effectual aid to Socrates; there is Critias assuming the tone of impartiality; Callias, here as always inclining to the Sophists, but eager for any intellectual repast; Prodicus, who finds an opportunity for displaying his distinctions of language, which are valueless and pedantic, because they are not based on dialectic; Hippias, who has previously exhibited his superficial knowledge of natural philosophy, to which, as in both the Dialogues called by his name, he now adds the profession of an interpreter of the Poets. The two latter personages have been already damaged by the mock heroic description of them in the introduction. It may be remarked that Protagoras is consistently presented to us throughout as the teacher of moral and political virtue; there is no allusion to the theories of sensation which are attributed to him in the Theaetetus and elsewhere, or to his denial of the existence of the gods in a well-known fragment ascribed to him; he is the religious rather than the irreligious teacher in this Dialogue. Also it may be observed that Socrates shows him as much respect as is consistent with his own ironical character; he admits that the dialectic which has overthrown Protagoras has carried himself round to a conclusion opposed to his first thesis. The force of argument, therefore, and not Socrates or Protagoras, has won the day.
But is Socrates serious in maintaining (1) that virtue cannot be taught; (2) that the virtues are one; (3) that virtue is the knowledge of pleasures and pains present and future? These propositions to us have an appearance of paradox they are really moments or aspects of the truth by the help of which we pass from the old conventional morality to a higher conception of virtue and knowledge. That virtue cannot be taught is a paradox of the same sort as the profession of Socrates that he knew nothing. Plato means to say that virtue is not brought to a man, but must be drawn out of him; and cannot be taught by rhetorical discourses or citations from the poets. The second question, whether the virtues are one or many, though at first sight distinct, is really a part of the same subject; for if the virtues are to be taught, they must be reducible to a common principle; and this common principle is found to be knowledge. Here, as Aristotle remarks, Socrates and Plato outstep the truth they make a part of virtue into the whole. Further, the nature of this knowledge, which is assumed to be a knowledge of pleasures and pains, appears to us too superficial and at variance with the spirit of Plato himself. Yet, in this, Plato is only following the historical Socrates as he is depicted to us in Xenophon's Memorabilia. Like Socrates, he finds on the surface of human life one common bond by which the virtues are united, their tendency to produce happiness, though such a principle is afterwards repudiated by him.
It remains to be considered in what relation the Protagoras stands to the other Dialogues of Plato. That it is one of the earlier or purely Socratic works perhaps the last, as it is certainly the greatest of them is indicated by the absence of any allusion to the doctrine of reminiscence; and also by the different attitude assumed towards the teaching and persons of the Sophists in some of the later Dialogues. The Charmides, Laches, Lysis, all touch on the question of the relation of knowledge to virtue, and may be regarded, if not as preliminary studies or sketches of the more important work, at any rate as closely connected with it. The Io and the lesser Hippias contain discussions of the Poets, which offer a parallel to the ironical criticism of Simonides, and are conceived in a similar spirit. The affinity of the Protagoras to the Meno is more doubtful. For there, although the same question is discussed, 'whether virtue can be taught,' and the relation of Meno to the Sophists is much the same as that of Hippocrates, the answer to the question is supplied out of the doctrine of ideas; the real Socrates is already passing into the Platonic one. At a later stage of the Platonic philosophy we shall find that both the paradox and the solution of it appear to have been retracted. The Phaedo, the Gorgias, and the Philebus offer further corrections of the teaching of the Protagoras; in all of them the doctrine that virtue is pleasure, or that pleasure is the chief or only good, is distinctly renounced.
Thus after many preparations and oppositions, both of the characters of men and aspects of the truth, especially of the popular and philosophical aspect; and after many interruptions and detentions by the way, which, as Theodorus says in the Theaetetus, are quite as agreeable as the argument, we arrive at the great Socratic thesis that virtue is knowledge. This is an aspect of the truth which was lost almost as soon as it was found; and yet has to be recovered by every one for himself who would pass the limits of proverbial and popular philosophy. The moral and intellectual are always dividing, yet they must be reunited, and in the highest conception of them are inseparable. The thesis of Socrates is not merely a hasty assumption, but may be also deemed an anticipation of some 'metaphysic of the future,' in which the divided elements of human nature are reconciled.
PERSONS OF THE DIALOGUE: Socrates, who is the narrator of the Dialogue to his Companion. Hippocrates, Alcibiades and Critias. Protagoras, Hippias and Prodicus (Sophists). Callias, a wealthy Athenian.
SCENE: The House of Callias.
COMPANION: Where do you come from, Socrates? And yet I need hardly ask the question, for I know that you have been in chase of the fair Alcibiades. I saw him the day before yesterday; and he had got a beard like a man, and he is a man, as I may tell you in your ear. But I thought that he was still very charming.
SOCRATES: What of his beard? Are you not of Homer's opinion, who says
'Youth is most charming when the beard first appears'?
And that is now the charm of Alcibiades.
COMPANION: Well, and how do matters proceed? Have you been visiting him, and was he gracious to you?
SOCRATES: Yes, I thought that he was very gracious; and especially to-day, for I have just come from him, and he has been helping me in an argument. But shall I tell you a strange thing? I paid no attention to him, and several times I quite forgot that he was present.
COMPANION: What is the meaning of this? Has anything happened between you and him? For surely you cannot have discovered a fairer love than he is; certainly not in this city of Athens.
SOCRATES: Yes, much fairer.
COMPANION: What do you mean a citizen or a foreigner?
SOCRATES: A foreigner.
COMPANION: Of what country?
SOCRATES: Of Abdera.
COMPANION: And is this stranger really in your opinion a fairer love than the son of Cleinias?
SOCRATES: And is not the wiser always the fairer, sweet friend?
COMPANION: But have you really met, Socrates, with some wise one?
SOCRATES: Say rather, with the wisest of all living men, if you are willing to accord that title to Protagoras.
COMPANION: What! Is Protagoras in Athens?
SOCRATES: Yes; he has been here two days.
COMPANION: And do you just come from an interview with him?
SOCRATES: Yes; and I have heard and said many things.