Other instances will occur to you, illustrating the importance of a broad outlook in the causation of disease or other forms of social misery. I will adduce one more. It is well known that infant mortality is much heavier among the poor than among the well-to-do. The rule does not hold universally in rural areas, but in towns it applies almost without exception. And it is assumed by a large school of social workers that enlightenment of the ignorance of the poor mother will effectively correct this evil. Such a lop-sided view ignores many of the elements of the problem of infant mortality. Think for a moment of the contrast between the working-class mother of five children living in a small city tenement, and the mother of an equal number of children in easy circumstances, living in a residential suburb, and having domestic servants, a nurse, and a physician always available. The two mothers probably differ but little in their knowledge of the hygiene of infancy; but the one has helpers to ensure scrupulous cleanliness, to prevent over-fatigue of the nursing mother, to detect the first sign of infantile illness and provide the needed action; while the other mother has to struggle alone in respect of her infant, without either domestic or nursing assistance, the struggle being complicated by the fact that the care of four older children and of her husband is on her shoulders. Even when there is no actual direct poverty in the working-class home, the differences thus indicated—supplemented by the inability of the mother to obtain medical advice for apparently minor ailments—outweigh enormously the factor of ignorance as a cause of excessive infant mortality. By all means let instruction be given by public health nurses or other agencies, and this is most valuable; but it does not fully meet the needs of the case. There is required also actual domestic, as well as nursing, assistance in the home of the overworked working-class mother, especially after the birth of her infant and when illness attacks any of her children; and unless the physician realises these elements in the problem, his efforts in securing the welfare of his patient and in reducing infant mortality can have but partial success. The main lessons arising from the foregoing illustrations of medical and social problems are two: Each evil should be attacked in its causal relationships; and causation is multiple. Hence—apart from total prohibition—in attacking alcoholism, the physician may bless the efforts of tee-total advocates, of those engaged in reducing the number of saloons, of those securing better dietetics and cooking, less industrial fatigue, or more satisfactory domestic sleeping accommodation, and of parents and teachers engaged in promoting self-control in the young as a habit of life; and he will call them all in aid of his curative and preventive life work.