The Nature of Suffering underscores the change that is taking place in medicine from a basic concern with disease to a greater focus on the sick person. Cassell centers his discussion on the problem of suffering because, he says, its recognition and relief are a test of the adequacy of any system of medicine. He describes what suffering is and its relationship to the sick person: bodies do not suffer, people do. An exclusive concern with scientific knowledge of the body and disease, therefore, impedes an understanding of suffering and diminishes the care of the suffering patient. The growing criticism that medicine is not sufficiently humanistic does not go deep enough to provide a basis for a new understanding of medicine. New concepts in medicine must have their basis in its history and in the development of ideas about disease and treatment. Cassell uses many stories about patients to demonstrate that, despite the current dominance of science and technology, there can be no diagnosis, search for the cause of the patient's disease, prognostication, or treatment without consideration of the individual sick person. Recent trends in medicine and society, Cassell believes, show that it is time for the sick person to be not merely an important concern for physicians but the central focus of medicine. He addresses the exciting problems involved in such a shift. In this new medicine, doctors would have to know the person as well as they know the disease. What are persons, however, and how are doctors to comprehend them? The kinds of knowledge involved are varied, including values and aesthetics as well as science. In the process of knowing the experience of patient and doctor move to center stage. He believes that the exploration of the person will engage medicine in the 21st century just as understanding the body has occupied the last hundred years.