Meanwhile the morality of Stoicism had enlisted a force of incalculable importance on its behalf. This was the life and death of the younger Cato. However narrow his intellect, however impracticable his principles, however hopeless his resistance to the course of history, Cato had merits which in the eyes of his countrymen placed him even higher than Caesar; and this impression was probably strengthened by the extraordinary want of tact which the great conqueror showed when he insulted the memory of his noblest foe. Pure in an age of corruption, disinterested in an age of greed, devotedly patriotic in an age of selfish ambition, faithful unto death in an age of shameless tergiversation, and withal of singularly mild and gentle character, Cato lived and died for the law of conscience, proving by his example that if a revival of old Roman virtue were still possible, only through the lessons of Greek philosophy could this miracle be wrought. And it was equally clear that Rome could only accept philosophy under a form harmonising with her ancient traditions, and embodying doctrines like those which the martyred saint of her republican liberties had professed.

The Roman reformers were satisfied to call themselves Stoics; and, in reviewing the Stoic system, we saw to what an extent they welcomed and developed some of its fundamental thoughts. But we have now to add that the current which bore them on had its source deeper down than the elaborate combinations of Zeno and Chrysippus, and entered into the composition of every other system that acted on the Roman intellect simultaneously with theirs. Thus whatever forces co-operated with Stoicism had the effect not of complicating but of simplifying its tendencies, by bringing into exclusive prominence the original impulse whence they sprang, which was the idea of Natural Law. Hence the form ultimately assumed by Roman thought was a philosophy of Nature, sometimes appearing more under a Stoic, and sometimes more under a Cynic guise. Everything in Roman poetry that is not copied from Greek models or inspired by Italian passion—in other words, its didactic, descriptive, and satiric elements—may be traced to this philosophy. Doubtless the inculcation of useful arts, the delight in beautiful scenery, the praises of rustic simplicity, the fierce protests against vice under all its forms, and the celebration of an imperial destiny, which form the staple of Rome’s national literature, spring from her own deepest life; but the quickening power of Greek thought was needed to develope them into articulate expression.

There is, indeed, nothing more nobly characteristic of the Hellenic spirit, especially as organised by Socrates, than its capacity not only for communicating, but for awakening ideas; thus enabling all the nations among which it spread to realise the whole potential treasure of theoretical and practical energy with which they were endowed. And, from this point of view, we may say that what seems most distinctively proper to Rome—the triumphant consciousness of herself as a world-conquering and world-ruling power—came to her from Greece, and under the form of a Greek idea, the idea of providential destiny. It was to make his countrymen understand the fateful character and inevitable march of her empire that Polybius composed his great history; it was also by a Greek that the most successful of her early national epics was sung; and when at last her language was wrought into an adequate instrument of literary expression—thanks also to Greek rhetorical teaching,—and the culture of her children had advanced so far that they could venture to compete with the Greeks on their own ground, it was still only under forms suggested by Stoicism that Virgil could rewrite the story of his country’s dedication to her predestined task.

That Virgil was acquainted with this philosophy and had accepted some of its principal conclusions is evident from a famous passage in the Sixth Aeneid,[282] setting forth the theory of a universal and all-penetrating soul composed of fiery matter, whence the particular souls of men and animals are derived, by a process likened to the scattering and germination of seeds; from another equally famous passage in the Fourth Eclogue,[283] describing the periodical recurrence of events in the same order as before; and also, although to a less extent, from his acceptance of the Stoic astronomy in the Georgics;[284] a circumstance which, by the way, renders it most unlikely that he looked up to Lucretius as an authority in physical science.[285] But even apart from this collateral evidence, one can see that the Aeneid is a Stoic poem. It is filled with the ideas of mutation and vicissitude overruled by a divinely appointed order; of the prophetic intimations by which that order is revealed; of the obedience to reason by which passion is subdued; and of the faith in divine goodness by which suffering is made easy to be borne. And there are also gleams of that universal humanity familiar to Stoicism, which read to some like an anticipation of the Christian or the modern spirit, but which really resemble them only as earlier manifestations of the same great philosophical movement.

This analogy with subsequent developments is aided, so far as it goes, by the admixture of a certain Platonic element with Virgil’s Stoicism, shown chiefly by the references to an antenatal existence of the soul, introduced for the purpose of bringing Rome’s future heroes on the scene. This, however, is the last example of an attempt on the part of a Roman writer to combine Plato’s teaching with Stoicism.[286] At a time when the Romans were more conscious of their literary dependence on Greece than was the case after the Augustan age had reached its zenith, they were probably drawn by the beauty of its literary form to study a system which could otherwise interest them but little. Thus, not only is Cicero full of admiration for Plato—as, indeed, might be expected with so highly cultivated a disciple of the Academy—but Cato, according to the well-known story, spent his last hours reading and re-reading the Phaedo; and his nephew Brutus also occupied an intermediate position between the Old Academy and the Porch. The Roman love of simplification and archaism induced subsequent thinkers either to let Platonism drop altogether, or to study those elements in which it differed from the pure naturalistic doctrine under their Pythagorean form. It may even be doubted whether Virgil’s psychology is not derived from Pythagoras rather than from Plato; Ovid, so far as he philosophises at all, is unquestionably a follower of the former;[287] and in the moral teaching of the Sextii, who flourished under Augustus, Pythagorean principles are blended with Stoicism.[288] It is another manifestation of the same effort to grasp every Greek doctrine by its roots, that Horace should proclaim himself the disciple of Aristippus rather than of Epicurus.[289] Even he, however, feels himself drawn with advancing years towards the nobler faith which was now carrying all before it.[290]

With Seneca and his contemporaries, Stoicism has shaken itself free from alien ingredients, and has become the accepted creed of the whole republican opposition, being especially pronounced in the writings of the two young poets, Persius and Lucan. But in proportion as naturalistic philosophy assumed the form of a protest against vice, luxury, inhumanity, despotism, and degradation, or of an exhortation to welcome death as a deliverance from those evils, in the same proportion did it tend to fall back into simple Cynicism; and on this side also it found a ready response, not only in the heroic fortitude, but also in the brutal coarseness and scurrility of the Roman character. Hence the Satires of the last great Roman poet, Juvenal, are an even more distinct expression of Cynic than the epic of Virgil had been of Stoic sentiment. Along with whatever was good and wholesome in Cynicism there is the shameless indecency of the Cynics, and their unquestioning acceptance of mendicancy and prostitution as convenient helps to leading a natural and easily contented life. And it may be noticed that the free-thinking tendencies which distinguished the Cynics from the Stoics are also displayed in Juvenal’s occasional denunciations of superstition.

X.

Thus the final effect of its communion with the Roman mind was not so much to develope Greek philosophy any further, or to reconcile its warring sects with one another, as to aid in their decomposition by throwing them back on the earlier forms whence they had sprung. Accordingly we find that the philosophic activity of Hellas immediately before and after the Christian era—so far as there was any at all—consisted in a revival of the Pythagorean and Cynic schools, accompanied by a corresponding resuscitation of primitive Scepticism. This last takes the shape of a very distinct protest against the fashionable naturalism of the age, just as the scepticism of Protagoras and Gorgias—if our view be correct—had once been called forth by the naturalism of Prodicus and Hippias. The principal representative, if not the founder, of Neo-Scepticism was Aenesidêmus, who taught in Alexandria, when we are not informed, but probably after the middle of the first century A.D.[291] An avowed disciple of Pyrrho, his object was to reassert the sceptical principle in its original purity, especially as against the Academicians, whom he charged with having first perverted and then completely abandoned it.[292] Aenesidêmus would hear nothing of probabilities nor of moral certainties. He also claimed to distinguish himself from the Academicians by refusing to assert even so much as that nothing can be asserted; but it appears that, in this point, he had been fully anticipated by Arcesilaus and Carneades.[293] For the rest, his own Scepticism recalls the method of Gorgias and Protagoras much more distinctly than the method of the New Academy—a fresh illustration of the archaic and revivalist tendencies displayed by philosophy at this period. In other words, it is not against the reasoning processes that his criticisms are directed, but against the theory of causation on the objective side, and against the credibility of our immediate perceptions on the subjective side.[294] But, in both directions, he has worked out the difficulties of the old Sophists with a minuteness and a precision unknown to them; and some of his points have been found worth repeating in a different connexion by modern critics. Thus, in analysing the theory of causation, he draws attention to the plurality of causes as an obstacle to connecting any given consequent with one antecedent more than with another; to the illegitimate assumption that the laws inferred from experience hold good under unknown conditions; to the arbitrary assumption of hypothetical causes not evinced by experience; and to the absurdity of introducing a new difficulty for the purpose of explaining an old one.[295] With regard to causation itself, Aenesidêmus seems to have resolved it into action and reaction, thus eliminating the condition of antecedence and consequence, without which it becomes unintelligible.[296]

The Alexandrian Sceptic’s general arguments against the possibility of knowledge resolve themselves into a criticism of what Sir W. Hamilton called Natural Realism, somewhat complicated and confused by a simultaneous attack on the theory of natural morality conceived as something eternal and immutable. They are summed up in the famous ten Tropes. Of these the first three are founded on the conflicting sensations produced by the same object when acting on different animals—as is inferred from the marked contrast presented by their several varieties of origin and structure,—on different men, and on the different senses of the same individual. The fourth, which has evidently an ethical bearing, enlarges on the changes in men’s views caused by mental and bodily changes, according to their health, age, disposition, and so forth. The next five Tropes relate to circumstances connected with the objects themselves: their distance and position as regards the spectator, the disturbance produced in their proper action by external influences such as air and light, together with the various membranes and humours composing the organs of sense through which they are apprehended; their quantitative variation, involving as it does opposite effects on the senses, or as with medicines, on the health; the law of relativity, according to which many things are only known when taken in company with others, such as double and half, right and left, whole and part; comparative frequency or rarity of occurrence, as with comets, which, while really of much less importance than the sun, excite much more interest from their being so seldom seen. Finally, the tenth Trope is purely ethical, and infers the non-existence of a fixed moral standard from the divergent and even opposite customs prevailing among different nations.[297]

In his attacks on the prevalent theories of ethics, Aenesidêmus again reminds us both of Protagoras and of modern agnosticism. According to him, the general disagreement of mankind proves, among other things, that there is no definable highest good—it is neither virtue, nor pleasure, nor knowledge.[298] In the absence of any dogmatic teaching on the subject at the time when he lived, Protagoras could not give an opinion with regard to the summum bonum; but Plato’s famous dialogue represents him as one who, from his point of view, would be unwilling to admit the possibility of introducing fixed principles into conduct; and in like manner, Mr. Herbert Spencer, while accepting the hedonistic principle, gives it such an extremely general signification that he is thrown back on the sceptical principle of leaving everyone free to follow his own inclinations, provided that, in so doing, he does not interfere with the liberty of others.