The problems of sociology are, in most instances, problems of preventive medicine, and many of the problems of preventive medicine resolve themselves into sociologic questions. The cure of disease in its larger aspect lies in its prevention in the individual, the community, the state. Medicine in its practical application must inevitably become almost wholly a problem of prevention. This involves its operation on the mass rather than the individual, and, therefore, it becomes a sociologic problem, with the knowledge acquired through the study of pure science to aid in its solution. Waiting for disease to arise in the individual, and then attacking it, involves an enormous economic waste, a waste of time, energy, earnings, efficiency, of life itself, to say nothing of the suffering, which causes a waste of nerve force, or of the tax on those immediately surrounding the individual and charged with his care. Likewise, philanthropy, state or private, directed to the relief of individual suffering and disease due directly or indirectly to faulty sociologic or industrial conditions, even though at present commendable and necessary from the humanitarian standpoint, means a tremendous waste. The vast public appropriations for hospitals and sanatoriums for the care of individuals suffering from contagious and infectious diseases—tuberculosis for instance—when weighed against prevention really constitute a waste. Prevention means the saving of most of this waste.