Whatever the causes of the change may have been, the conditions of public life in this Hellenistic period were certainly very different from those which prevailed, albeit with decadence, before that vast breaking up of boundaries and destruction of political systems involved in the Macedonian conquests. The successful and inspiring conflict with Persia waged by the Hellenic States had for a time made all Greek hearts to beat with one aspiration, and had brought to the front a race of leaders who were capable of subduing the Greek democracies to their own steadfast and statesmanlike purposes. Public life was then not only a possible but even the most natural career for a man of talent and probity. The small size of the Greek States gave almost every such man an opportunity of action, and so keen and universal was the interest in politics that it threatened to lead Greek philosophy into a region in which philosophy is very apt to lose its vitalizing connection with human consciousness and experience, and to stiffen into barren speculation. In a word, man, as an individual, began to be too much lost sight of in the consideration of man as a citizen; his uses, his duties, the whole worth and significance of his life, came to be estimated too exclusively by his relations to the visible society about him. It was when the great Stoic Chrysippus found himself obliged to stand aloof from all participation in politics—“For if I counsel honorably I shall offend the citizens, and if basely, the Gods”—that such men as he were led to ask themselves: Is there then any sphere of human endeavor out of the reach of the tyranny of circumstance? If I cannot be a citizen, what am I worth then simply as a man? If I can be nothing to my fellows, what can I be to God? To a state of things, then, which, speaking broadly, made public life impossible to honest men, we owe the noblest ethical system of antiquity; to the enforced concentration of thought upon the individual we owe a certain note of universality till then absent from Hellenic thought. But stoicism was not the only product of the speculation of this period. Side by side with it there started into being two other systems of philosophy, the necessity for combating which was doubtless of immense service to its development. These were Epicureanism and Pyrrhonism; and as the reader will find Epictetus much concerned with each of them, it may be desirable that I should give some brief account of their cardinal doctrines.