These civilizations have a second characteristic at which the observer cannot but feel surprise, namely, their singular longevity and immobility. No doubt when we examine them closely we see that they changed, like everything else that is born, that lives and dies; but the changes only took place with extreme slowness. In the course of three or four thousand years beliefs and mental ideas could hardly remain quite stationary, but the forms and ceremonies of religion varied in no appreciable degree. We may say the same of manners and social institutions. These could not, of course, remain quite the same during such a lapse of time; a single word, for instance, may have changed its meaning more than once in so many centuries; but it is none the less true that the conservative spirit, as we should call it, had a permanent force that it seems to have lost in the west, amid the rapid transformations and perpetual mobility of our modern world. And we must recollect that these societies did not escape any more than others from the disorders of civil war, of political revolutions or barbarian inroads. Like all other human systems, they were subject to catastrophes which must have thrown everything into confusion for a time. But after each crisis had spent its force the ranks were closed and dressed, like those of a well-disciplined regiment after receiving a destructive volley. When quiet had come again men returned to their places in the framework of a society closely bound together by habits formed during countless generations. This framework had been so patiently elaborated and co-ordinated, it was so elastic, and, at the same time, so full of resistance, that even a foreign master found it more politic to preserve it and fall in with its ways than to destroy it; he was content, in most cases, to step into the place occupied by the prince whom he ousted. Affairs thus fell into their accustomed groove as soon as a conquest was complete; classes were reconstituted on their old bases; property and people took up their former conditions; the only difference lay in the fact that a new group of privileged individuals shared the wealth created by agricultural, industrial, and commercial activity. The sovereign and his chief officers might be of foreign race, but the social machine rolled on over the same road and with the same wheels as before. The effect of this uniform and continuous movement did not stop here: it had another consequence in the rapid assimilation of heterogeneous and accidental elements, which adapted themselves in a very short time to the mould into which they were pushed and pressed by the never-sleeping action of an intense organic life, until, in time, they became fused and lost in the life they had meant to dominate.