The common factor in medical specialism can only be described in negative terms. A specialist is one who does not practice comprehensive medicine. He exercises his skills only in some subdivision or in some partial function within the larger framework of medicine. The summation of the practices of the specialities does not, in effect, constitute the practice of comprehensive medicine. As a science, ecology is the study and exposition of the multiple, and often of the subtle, effects, which both living and nonliving entities exercise one on another, and the many among themselves. As far as man is concerned, ecology is a humbling and a leveling science. It reveals that in the embracing scheme of things, in the scales of ecologic nature, man weighs no more ponderously than does the vibrio of cholera, the spirochete of syphilis, or the bacillus of phthisis. Man is the only one of nature's creatures who has learned how to manipulate ecologic nature. Diseases have been conquered not by the clinical or surgical specialties but by ecologic and physiological medicine. The future of medical service is not to be envisaged as a continued refinement, as well as increase, in the specialties, with the consequent parceling out of the patient to a host of men, who will care for him and treat his illnesses. Rather, within two generations, medicine as a science, and medical care, will undergo a revolutionary change brought about not by the economic, legislative, or social manipulations of well-meaning men but by the maturation of those knowledges and intelligences embraced in physiological, and in ecologic, medicine.