civilized man has proceeded so far in his interference with extra-human nature, has produced for himself and the living organisms associated with him such a special state of things by his rebellion against natural selection and his defiance of Nature's pre-human dispositions, that he must either go on and acquire firmer control of the conditions, or perish miserably by the vengeance certain to fall on the half-hearted meddler in great affairs. We may indeed compare civilized man to a successful rebel against Nature, who, by every step forward, renders himself liable to greater and greater penalties, and so cannot afford to pause or fail in one single step. Or again we may think of him as the heir to a vast and magnificent kingdom, who has been finally educated so as to take possession of his property, and is at length left alone to do his best; he has wilfully abrogated, in many important respects, the laws of his mother Nature by which the kingdom was hitherto governed; he has gained some power and advantage by so doing, but is threatened on every hand by dangers and disasters hitherto restrained: no retreat is possible--his only hope is to control, as he knows that he can, the sources of these dangers and disasters. The time will come, not too long hence, as I believe, when men have realized, with the scientists, that the world is one kingdom not many, and these problems of man's relation to his non-human environment will be the first concern of statesmen and governors. In some of our tropical colonies they have, perforce, become so already. If you live on the Gold Coast, the war against malaria cannot help seeming more important to you than the war against German trade: and in parts of Central Africa the whole possibility of continued existence centres round the presence or absence of the tsetse fly which is the carrier of sleeping sickness. Some day, when means have been adopted for abating our fiercer international controversies, we shall discover that in these and kindred matters lies the real province of world-politics. When that day comes the chosen representatives of the human race will see their constituents, as only philosophers see them now, as the inheritors of a great tradition of service and achievement, and as trustees for their successors of the manifold sources of human happiness which the advance of knowledge has laid open to us.