Thus the same act may be for the undeveloped life, non-moral, for the developed, distinctly immoral. Before the instincts of personal modesty and purity were developed, careless sex-promiscuity meant something entirely different from what a descent to it means in our society. When a man of some primitive tribe went out and killed a man of another tribe, the action was totally different morally from .the murder by a man of one community of a citizen of a neighboring town to-day. This gradual elevation of moral standards, or growth in the recognition of the sacredness of life and the obligation to other individuals, can be traced historically as a long and confused process. There was a time, in the remote past, when no law was recognized except that of the strong arm. The man who wanted anything, took it, if he was strong enough, and others submitted to his superior force. Then follows an age when the family is the supreme social unit. Each member of the family group feels the pain or pleasure of all the others as something like his own, but all outside this circle are as the beasts. This is the condition among the Veddahs of Ceylon, studied so interestingly by Haeckel. Living in isolated family groups, scattered through the tropical wilderness: one man, one woman and their children forming the social unit: they as nearly represent primitive life as any other body of people now on the earth. Then follows a long roll of ages when the tribe is the highest social unit. Each member of the tribe is conscious of the sacredness of life of all the other members and of some obligation toward them; but men of other tribes may be slain as freely as the beasts. Then comes a period when appreciation of the sacredness of life is extended over all those of the same race, tested generally by their speaking somewhat the same language. That was the condition in classic antiquity: it was "Jew and Gentile," "Greek and barbarian"--the very word "barbarous" coming from the unintelligible sounds, to the Greeks, of those who spoke other than the Hellenic tongue. Even Plato, with all his far-sighted humanism, says, in the _Republic_, that in the ideal state, "Greeks should deal with barbarians as Greeks now deal with one another." If one remembers what occurred in the Peloponnesian war--how Greek men voted to kill all the men of military age in a conquered Greek city and sell all the women and children into slavery--one will see that Plato's dream of humanity was not so very wide.