The anthropological sciences are those from which, _a priori_, we might have expected the greatest social effects, but hitherto this has not proved to be the case, partly because these sciences are mostly still at an early stage of development. Even economics has not so far had much effect. Where it has seemed to have, this is because it advocated what was independently desired. Hitherto, the most effective of the anthropological sciences has been medicine, through its influence on sanitation and public health, and through the fact that it has discovered how to deal with malaria and yellow fever. Birth-control is also a very important social fact which comes into this category. But although the future effect of the anthropological sciences (to which I shall return presently) is illimitable, the effect up to the present has been confined within fairly narrow limits. One general observation to begin with. Science has increased man’s control over nature, and might therefore be supposed likely to increase his happiness and well-being. This would be the case if men were rational, but in fact they are bundles of passions and instincts. An animal species in a stable environment, if it does not die out, acquires an equilibrium between its passions and the conditions of its life. If the conditions are suddenly altered, the equilibrium is upset. Wolves in a state of nature have difficulty in getting food, and therefore need the stimulus of a very insistent hunger. The result is that their descendants, domestic dogs, over-eat if they are allowed to do so. When a certain amount of something is useful, and the difficulty of obtaining it is diminished, instinct will usually lead an animal to excess in the new circumstances. The sudden change produced by science has upset the balance between our instincts and our circumstances, but in directions not sufficiently noticed. Over-eating is not a serious danger, but over-fighting is. The human instincts of power and rivalry, like the dog’s wolfish appetite will need to be artificially curbed, if industrialism is to succeed. II. EFFECTS OF THE PHYSICAL SCIENCES Much the greatest part of the changes which science has made in social life is due to the physical sciences, as is evident when we consider that they brought about the industrial revolution. This is a trite topic, about which I shall say as little as my subject permits. There are, however, some points which must be made.