But along with this growth in the scale of conflict we have a complication which makes it something essentially different from a mere enlargement of the struggles of primitive tribes. Groups have become multiform and intersecting, so that the national competition which succeeds to the tribal is only one of a vast system of interactions. There are groups of every size, from two or three persons up to millions; their purposes are countless, their methods equally so. We can no longer see mankind as broken up into distinct wholes struggling for similar ends in a similar manner; we see many systems of struggle which interpenetrate one another, the same men taking part in various systems, so that the lines of alliance and opposition are inextricably entangled. Modern life, even when viewed as conflict, is an organic whole which it is impossible to break up into fragments. Group struggle has, on the whole, tended to rise to higher levels of intelligence and moral control in accordance with the increasing mental and moral unification of life. History shows a general growth of rational organization; and this means, for one thing, a general situation in which intelligence and the control of the part in the interest of the whole more and more condition every kind of success. International struggles are affected by this trend, as are all other kinds. Special associations which cross national lines, such as those of commerce, labor, science and philanthropy, increase, and so also do the informal bonds of literature, art and public sentiment. It is more and more apparent that the national bond is only one, though in some respects the most important one, in a growing network of relations. It is the nature of solidarity to react upon and control destructive forms of activity. In so far as life is organic a harm done to the part comes to be a harm done to the whole, and to be felt as such. If it is true that common interests of some kind unite every sort of men with every other, then it is no longer possible to divide man into separate and merely hostile wholes. There was never before so much to lose by an outbreak of violence, and we have seen how a modern war can become a world-calamity, arousing a universal determination to prevent its repetition. And although this may prove ineffectual and war may recur, it must be true, if man has power over his own destiny, that it is, on the whole, obsolescent. The principle applies also to international or interracial bad faith or ill will. It is not too much to say that the whole world is becoming one body, so that evil appearing in one part is felt as a menace to all the others.