of the Stoics, professing to follow the example of Socrates, though they thought that even he had approached too near to dogmatism in saying that he knew that he knew nothing. Probable opinion was the furthest point in the direction of knowledge to which man could attain.

Cicero, in his Natura Deorum and Academica, and Sextus Empiricus have preserved to us several specimens of the arguments used by Carneades in order to prove the impossibility of the attainment of knowledge in the abstract, as well as to expose the errors and inconsistency of the knowledge professed by the Dogmatic schools of his time. Thus, if there is such a thing as knowledge, it must rest ultimately on the senses; but the senses are constantly deceptive, and we have no means of distinguishing between a true and a false sensation, the difference between objects being often so imperceptible that we are liable to mistake one for another. The impotence of reasoning as an instrument for the attainment of certain truth is shown by the Sorites and other logical puzzles. Dialectic only tests formal accuracy of procedure, it cannot assure us of the truth of that which we assume as the foundation of our reasoning. Like the polypus which feeds on its own limbs, it can destroy, but never establish proof. The Stoics allege universal consent as a proof of the existence of God. But this consent is not proved, and, if it were, the opinion of the ignorant has no weight. The Stoics further maintain that the world exhibits the perfection of reason in its constitution and that Divine Providence directs all things for the good of men. But many things exist for which we can see no reason, many which are distinctly injurious to mankind. Even the possession of reason is a very doubtful advan

tage; and we do not find that the wise and virtuous man is always prosperous. Granting that the world is perfect, why may not this perfection be the result of the unconscious working of nature? Why are we bound to attribute it to the action of an intelligent Being? Again it is impossible to form any consistent conception of God. The ideas of personality and infinity are mutually contradictory. Even to think of Him as the living God or the good God, is opposed to reason. For animal life is necessarily joined with feeling, and feeling implies consciousness of pleasure and pain, but whatever is capable of pain is liable to destruction by excess of pain. And how can we ascribe virtue to a Being who is supposed to have no weaknesses to conquer, no temptations to resist; who being all-powerful can have no need of prudence to devise means for attaining his ends, no need of courage to sustain him against danger? It is equally impossible to think of God either as corporeal or incorporeal. If he is the former, he must be either simple or compound: if he is compounded of different elements, he is naturally liable to dissolution; if he is a pure elementary substance, he must be without life and thought. On the other hand that which is incorporeal can neither feel nor act. In like manner it may be shown that it is impossible to make any assertion whatever about God.

But though knowledge and certainty are unattainable, we are not left simply to act at hazard. Probability was the guide of life to Carneades, as to Bp. Butler; and he carefully distinguished degrees of probability. Thus a sensation might be of such a nature as to produce in us belief involuntarily; this he called pavraoía milavý, a persuasive presentation. Again, no sensation comes

singly, and any one sensation is liable to be confirmed or weakened by the connected sensations. We may believe, for instance, that we see the figure of Socrates; and this belief will be confirmed if we think we recognize his voice. If then all the associated sensations agree in confirming our belief, such a belief is called pavraoía άTEρíoπασтоs, an undisturbed presentation. The highest degree of probability is when we have further investigated the conditions under which the sensation occurred (such as the soundness of the organ, the distance from the object etc.), and find nothing to raise suspicion as to its reality; belief is then called φαντασία περιωδευμένη, α thoroughly explored presentation. We have very little information as to the particular doctrines to which Carneades assigned probability. One tradition says that in his old age, he relaxed in his irony, and became more free-spoken', but his successor Clitomachus professed that he had never been able to ascertain what his real belief was3.

The Reformed Academy may be regarded as commencing with Philo of Larissa, a pupil of Clitomachus and one of Cicero's teachers. In it we see a return to dogmatism combined with an eclectic tendency which showed itself most strongly in Philo's pupil Antiochus, who endeavoured to strengthen the Academy by uniting Stoic and Peripatetic doctrines with the original Platonism. Further details will be given when we come to speak of the influence of the Roman spirit on the development of philosophy.

We turn now to the two most important developments of post-Aristotelian philosophy, Stoicism and Epicureanism. To understand them it is necessary to look for a 2 Cic. Acad. II. 139.

1 See Zeller III. I. p. 5313.

moment at the changes which had been brought about by the conquests of Alexander. While Greece proper lost

its national life, the Greek language and Greek civilization spread throughout the world, and the Greeks in their turn became familiarized with Oriental thought and religion. Thus the two main supports of the authoritative tradition by which practical life had hitherto been regulated, the law of the State and the old religion of Greece, were shaken from their foundations. The need which was most strongly felt by the best minds was to find some substitute for these, some principle of conduct which should enable a man to retain his self-respect under the rule of brute force to which all were subject. It must be something which would enable him to stand alone, to defy the oppressor, to rise superior to circumstances. Such a principle the Stoics boasted to have found1. Zeno, the founder of the school, was a native of Citium in Cyprus. He came to Athens about 320 B.C. and attended the lectures of Crates the Cynic and afterwards of Stilpo the Megarian and of some of the Academics, and began to teach in the σroά Tokiλn about 308 B.C. He was succeeded by Cleanthes of Assos in Asia Minor about 260 B.C. Among his other pupils were Aristo of Chius, Herillus of Carthage, Persaeus, who like his master was a native of Citium, and Aratus of Soli in Cilicia, the author of two astronomical poems translated by Cicero (N. D. II. 104-115). Cleanthes was succeeded by Chrysippus of Soli (b. 280, d. 206), who did so much to develop and systematize the Stoic philosophy that he was called the Second Founder of the

1 See the interesting treatise on Stoicism by W. W. Capes in the S. P. C. K. series, and Essay VI of the Introduction to Grant's Ethics.

school'. Next came Zeno of Tarsus and Diogenes of Babylon, one of the three ambassadors to Rome in 155 B.C. From this time forward Stoicism begins to show a softened and eclectic tendency, as we may see in Panaetius of Rhodes (180-III B.C.), and also in his pupil Posidonius of Apamea in Syria, of whom we shall have more to say hereafter.

The end of philosophy with the Stoics was purely practical. Philosophy is identical with virtue. But since virtue consists in bringing the actions into harmony with the general order of the world, it is essential to know what this order is, and thus we arrive at the famous triple division of philosophy into physics, including cosmology and theology, which explains the nature and laws of the universe; logic, which ensures us against deception and supplies the method for attaining to true knowledge; ethics, which draws the conclusion for practical life. The Stoics were famed for their logical subtilties, and are often referred to under the name Dialectici. They included in Logic both Rhetoric and Grammar, and made great improvements in the theory of the latter subject. The chief point of interest however in their Logic is their theory as to the criterion. They considered the soul to resemble a sheet of blank paper on which impressions (pavraoía) were made through the senses.

1 Cf. the line εἰ μὴ γὰρ ἦν Χρύσιππος οὐκ ἂν ἦν στοά.

2 Plut. Plac. Phil. IV. II.

3 Cleanthes held that each impression was literally a material impression on the soul, like that of a signet-ring on wax: Chrysippus thought this inconsistent with the infinite variety of impressions which we are continually receiving, and preferred to speak of them as modifications (èrepowσeis) of the soul. See Sext. Math. VII. 228.