The quality of medical practice, research, and education depends considerably on the image medical professionals, researchers, and teachers have of their discipline because that image determines the modes of their professional, scientific, and educational conduct. This image refers to what they usually term "the nature of medicine". Accordingly, the nature of medicine is often a central theme in metamedical discussions concerned with the question " what is medicine?". Is it a natural science? Is it an applied science? Is it an A or a B or a C? The preceding chapters revealed many new and interesting features of medicine, casting a new light on that question.