That the alleged unchangeability of human nature in this matter is not borne out; that man's pugnacity though not disappearing, is very visibly, under the forces of mechanical and social development, being transformed and diverted from ends that are wasteful and destructive to ends that are less wasteful, which render easier that co-operation between men in the struggle with their environment which is the condition of their survival and advance; that changes which, in the historical period, have been extraordinarily rapid are necessarily quickening--quickening in geometrical rather than in arithmetical ratio. With very great courtesy, one is impelled to ask those who argue that human nature in all its manifestations must remain unchanged how they interpret history. We have seen man progress from the mere animal fighting with other animals, seizing his food by force, seizing also by force his females, eating his own kind, the sons of the family struggling with the father for the possession of the father's wives; we have seen this incoherent welter of animal struggle at least partly abandoned for settled industry, and partly surviving as a more organized tribal warfare or a more ordered pillaging, like that of the Vikings and the Huns; we have seen even these pillagers abandon in part their pillaging for ordered industry, and in part for the more ceremonial conflict of feudal struggle; we have seen even the feudal conflict abandoned in favor of dynastic and religious and territorial conflict, and then dynastic and religious conflict abandoned. There remains now only the conflict of States, and that, too, at a time when the character and conception of the State are being profoundly modified. Human nature may not change, whatever that vague phrase may mean; but human nature is a complex factor. It includes numberless motives, many of which are modified in relation to the rest as circumstances change; so that the manifestations of human nature change out of all recognition. Do we mean by the phrase that "human nature does not change" that the feelings of the paleolithic man who ate the bodies of his enemies and of his own children are the same as those of a Herbert Spencer, or even of the modern New Yorker who catches his subway train to business in the morning? If human nature does not change, may we therefore expect the city clerk to brain his mother and serve her up for dinner, or suppose that Lord Roberts or Lord Kitchener is in the habit, while on campaign, of catching the babies of his enemies on spear-heads, or driving his motor-car over the bodies of young girls, like the leaders of the old Northmen in their ox-wagons.