Yet the Stoics were not altogether alien to the ordinary interests and duties of life. They admitted a duty of co-operating in politics, at least in such states as showed some desire for, or approach to, virtue. They approved of the wise man taking part in education, of his marrying and bringing up children, both for his own sake and his country's. He will be ready even to 'withdraw himself from life on behalf of his country or his friends. This 'withdrawal,' which was their word for suicide, came unhappily to be much in the mouths of later, and especially of the Roman, Stoics, who, in the sadness and restraint of prevailing despotism, came to thank God that no one was compelled to remain in life; he might 'withdraw' when the burden of life, the hopelessness of useful activity, became too great. With this sad, stern, yet not undignified note, the philosophy of Greece speaks its last word. The later scepticism of the New Academy, directed mainly to a negative criticism of the crude enough logic of the {242} Stoics, or of the extravagances of their ethical doctrine, contributed no substantial element to thought or morals. As an eclectic system it had much vogue, side by side with Stoicism and Epicureanism, among the Romans, having as its chief exponent Cicero, as Epicureanism had Lucretius, and Stoicism, Seneca. The common characteristic of all these systems in their later developments, is their _cosmopolitanism_. _Homo sum, nil humani a me alienum puto_, 'I am a man; nothing appertaining to humanity do I deem alien from myself,' this was the true keynote of whatever was vital in any of them. And the reason of this is not far to seek. We have seen already (p. 82) how the chaos of sophistic doctrine was largely conditioned, if not produced, by the breakdown of the old civic life of Greece. The process hardly suffered delay from all the efforts of Socrates and Plato. Cosmopolitanism was already a point of union between the Cynics and Cyrenaics (see p. 128). And the march of politics was always tending in the same direction. First through great leagues, such as the Spartan or Athenian or Theban, each with a predominant or tyrannical city at the head; then later through the conquest of Greece by Alexander, and the leaguing of all Greek-speaking peoples in the great invasion of Asia; then through the spread of Greek letters all over the Eastern {243} world, and the influx upon Greek centres such as Athens and Alexandria, of all manner of foreign intelligences; and finally, through the conquest of all this teeming world of culture by the discipline and practical ability of Rome, and its incorporation in a universal empire of law, all the barriers which had divided city from city and tribe from tribe and race from race disappeared, and only a common humanity remained.