Pyrrho and his followers, having proved the impossibility of a science superhuman in its height being reached by unaided man, supposed they had destroyed all knowledge and certainty whatever. The state of Athens then was particularly unsatisfactory. Old creeds were tottering. The spiritual life of Greece was decaying, as was its national. Men wanted some refuge from the distractions of their minds. Their spiritual nature, their soul, began to exert its power, to speak in tones that would be heard. The mind had been trying to still its craving with the noble but unsatisfying theories of Plato, or the subtleties of Aristotle. But the soul, the inner life, had been uncared for. Now it claimed its share of attention and new schools arose to satisfy, as far as they could, the newly felt longings. At such a time, Zeno founded his system. When Greece was tottering and falling into ruin, out of materials which I have shown to be so contradictory, he built up a structure which outlasted Greece, and was removed (altered a little, but in the main the same), to the new centre of the civilization and power of the world. His system lasted from his day to the time of Marcus Aurelius. It was embraced by the Romans with eagerness, as being congenial with their nature, before they became corrupted by their unrivalled prosperity. When at length it had done its destined work in the world, it yielded to a mightier and holier influence; leaving, however, its impress on the souls of men, even as, before its own decay, it received some of the rays of divine light which came from heaven with the Son of GOD, though it did not acknowledge the boon. It would be beside the purpose of the present essay to enter into all the specialities of the Zenonic doctrines; or to enquire at large, how far Zeno differed from Plato, or how nearly he agreed with Aristotle, in defining the manner of perception by the mind. We need not discuss τὴν καταληπτικὴν φαντασίαν, which Sextus Empiricus alleges to have been held by Zeno and his successors as the one means of judging true from false; respecting which even Cleanthes and Chrysippus differed[14]. An outline of the main features of the system will be sufficient. As I have before said, the first Stoic fixed his thoughts chiefly on moral conduct. His philosophy was eminently practical. It referred to the daily life. In order to stem the torrent of scepticism and sensuality, he taught men the value, the absolute necessity, of virtue. They were to apply his dogmas to their daily experience. They were not to speculate, but to act; not to doubt, but to dare. He taught them also that what Socrates had said was true, that the knowledge and practice of good was virtue and wisdom, that vice was therefore error in its worst form. In order to induce men to conform to this knowledge in their way of life, he unfolded to them how they were related to the universe.