It is fairly obvious that the time when the disappearance takes place will vary considerably, according to circumstances. Yet it does finally come to pass, and is everywhere quite complete, long before the end of the civilization which the victorious race is supposed to be animating. A people may often go on living and working, and even growing in power, after the active, generating force of its life and glory has ceased to exist. Does this contradict what I have said above? Not at all; for while the blood of the civilizing race is gradually drained away by being parcelled out among the peoples that are conquered or annexed, the impulse originally given to these peoples still persists. The institutions which the dead master had invented, the laws he had prescribed, the customs he had initiated—all these live after him. No doubt the customs, laws, and institutions have quite forgotten the spirit that informed their youth; they survive in dishonoured old age, every day more sapless and rotten. But so long as even their shadows remain, the building stands, the body seems to have a soul, the pale ghost walks. When the original impulse has worked itself out, the last word has been said. Nothing remains; the civilization is dead. I think I now have all the data necessary for grappling with the problem of the life and death of nations; and I can say positively that a people will never die, if it remains eternally composed of the same national elements. If the empire of Darius had, at the battle of Arbela, been able to fill its ranks with Persians, that is to say with real Aryans; if the Romans of the later Empire had had a Senate and an army of the same stock as that which existed at the time of the Fabii, their dominion would never have come to an end. So long as they kept the same purity of blood, the Persians and Romans would have lived and reigned. In the long run, it might be said, a conqueror, more irresistible than they, would have appeared on the scene; and they would have fallen under a well-directed attack, or a long siege, or simply by the fortune of a single battle. Yes, a State might be overthrown in this way, but not a civilization or a social organism. Invasion and defeat are but the dark clouds that for a time blot out the day, and then pass over. Many examples might be brought forward in proof of this. In modern times the Chinese have been twice conquered. They have always forced their conquerors to become assimilated to them, and to respect their customs; they gave much, and took hardly anything in return. They drove out the first invaders, and in time will do the same with the second.