Protagoras was born about 480 B.C. He was a fellow-townsman of Democritus, and has been represented, though not on good authority, as a disciple of that illustrious thinker. It was rather by a study of Heracleitus that his philosophical opinions, so far as they were borrowed from others, seem to have been most decisively determined. In any case, practice, not theory, was the principal occupation of his life. He gave instruction for payment in the higher branches of a liberal education, and adopted the name of Sophist, which before had simply meant a wise man, as an honourable title for his new calling. Protagoras was a very popular teacher. The news of his arrival in a strange city excited immense enthusiasm, and he was followed from place to place by a band of eager disciples. At Athens he was honoured by the friendship of such men as Pericles and Euripides. It was at the house of the great tragic poet that he read out a work beginning with the ominous declaration, ‘I cannot tell whether the gods exist or not; life is too short for such difficult investigations.’66 Athenian bigotry took alarm directly. The book containing this frank confession of agnosticism was publicly burned, all purchasers being compelled to give up the copies in their possession. The author himself was either banished or took flight, and perished by shipwreck on the way to Sicily before completing his seventieth year.
The scepticism of Protagoras went beyond theology and extended to all science whatever. Such, at least, seems to have been the force of his celebrated declaration that ‘man is the measure of all things, both as regards their existence and their non-existence.’67 According to Plato, this doctrine followed from the identification of knowledge with sensible perception, which in its turn was based on a modified form of the Heracleitean theory of a perpetual flux. The series of external changes which constitutes Nature, acting on the series of internal changes which constitutes each man’s personality, produces particular sensations, and these alone are the true reality. They vary with every variation in the factors, and therefore are not the same for separate individuals. Each man’s perceptions are true for himself, but for himself alone. Plato easily shows that such a theory of truth is at variance with ordinary opinion, and that if all opinions are true, it must necessarily stand self-condemned. We may also observe that if nothing can be known but sensation, nothing can be known of its conditions. It would, however, be unfair to convict Protagoras of talking nonsense on the unsupported authority of the Theaetêtus. Plato himself suggests that a better case might have been made out for the incriminated doctrine could its author have been heard in self-defence. We may conjecture that Protagoras did not distinguish very accurately between existence, knowledge, and applicability to practice. If we assume, what there seems good reason to believe, that in the great controversy of Nature versus Law, Protagoras sided with the latter, his position will at once become clear. When the champions of Nature credited her with a stability and an authority greater than could be claimed for merely human arrangements, it was a judicious step to carry the war into their territory, and ask, on what foundation then does Nature herself stand? Is not she, too, perpetually changing, and do we not become acquainted with her entirely through our own feelings? Ought not those feelings to be taken as the ultimate standard in all questions of right and wrong? Individual opinion is a fact which must be reckoned with, but which can be changed by persuasion, not by appeals to something that we none of us know anything about. Man is the measure of all things, not the will of gods whose very existence is uncertain, nor yet a purely hypothetical state of Nature. Human interests must take precedence of every other consideration. Hector meant nothing else when he preferred the obvious dictates of patriotism to inferences drawn from the flight of birds.
We now understand why Protagoras, in the Platonic dialogue bearing his name, should glance scornfully at the method of instruction pursued by Hippias, with his lectures on astronomy, and why he prefers to discuss obscure passages in the poets. The quarrel between a classical and a scientific education was just then beginning, and Protagoras, as a Humanist, sided with the classics. Again, he does not think much of the ‘great and sane and noble race of brutes.’ He would not, like the Cynics, take them as examples of conduct. Man, he says, is naturally worse provided for than any animal; even the divine gift of wisdom would not save him from extinction without the priceless social virtues of justice and reverence, that is, the regard for public opinion which Mr. Darwin, too, has represented as the strongest moralising power in primitive society. And, as the possession of these qualities constituted the fundamental distinction between men and brutes, so also did the advantage of civilisation over barbarism rest on their superior development, a development due to the ethical instruction received by every citizen from his earliest infancy, reinforced through after-life by the sterner correction of legal punishments, and completed by the elimination of all individuals demonstrably unfitted for the social state. Protagoras had no sympathy with those who affect to prefer the simplicity of savages to the fancied corruption of civilisation. Hear how he answers the Rousseaus and Diderots of his time:—
‘I would have you consider that he who appears to you to be the worst of those who have been brought up in laws and humanities would appear to be a just man and a master of justice if he were to be compared with men who had no education, or courts of justice, or laws, or any restraints upon them which compelled them to practise virtue—with the savages, for example, whom the poet Pherecrates exhibited on the stage at the last year’s Lenaean festival. If you were living among men such as the man-haters in his chorus, you would be only too glad to meet with Eurybates and Phrynondas, and you would sorrowfully long to revisit the rascality of this part of the world.’68
We find the same theory reproduced and enforced with weighty illustrations by the great historian of that age. It is not known whether Thucydides owed any part of his culture to Protagoras, but the introduction to his history breathes the same spirit as the observations which we have just transcribed. He, too, characterises antiquity as a scene of barbarism, isolation, and lawless violence, particularly remarking that piracy was not then counted a dishonourable profession. He points to the tribes outside Greece, together with the most backward among the Greeks themselves, as representing the low condition from which Athens and her sister states had only emerged within a comparatively recent period. And in the funeral oration which he puts into the mouth of Pericles, the legendary glories of Athens are passed over without the slightest allusion,69 while exclusive prominence is given to her proud position as the intellectual centre of Greece. Evidently a radical change had taken place in men’s conceptions since Herodotus wrote. They were learning to despise the mythical glories of their ancestors, to exalt the present at the expense of the past, to fix their attention exclusively on immediate human interests, and, possibly, to anticipate the coming of a loftier civilisation than had as yet been seen.
The evolution of Greek tragic poetry bears witness to the same transformation of taste. On comparing Sophocles with Aeschylus, we are struck by a change of tone analogous to that which distinguishes Thucydides from Herodotus. It has been shown in our first chapter how the elder dramatist delights in tracing events and institutions back to their first origin, and in following derivations through the steps of a genealogical sequence. Sophocles, on the other hand, limits himself to a close analysis of the action immediately represented, the motives by which his characters are influenced, and the arguments by which their conduct is justified or condemned. We have already touched on the very different attitude assumed towards religion by these two great poets. Here we have only to add that while Aeschylus fills his dramas with supernatural beings, and frequently restricts his mortal actors to the interpretation or execution of a divine mandate, Sophocles, representing the spirit of Greek Humanism, only once brings a god on the stage, and dwells exclusively on the emotions of pride, ambition, revenge, terror, pity, and affection, by which men and women of a lofty type are actuated. Again (and this is one of his poetic superiorities), Aeschylus has an open sense for the external world; his imagination