The complex theory developed by C.G. Jung and his insights into emotion, imagination, and the creative power of the psyche prepared the way for current research on the effects of placebos and interactions between the psyche and the immune system. Jung=s conception of the body&mind relationship is helpful in overcoming inappropriate notions of causality and blame. According to the theory, prevention and treatment of physical diseases are not possible without taking the psyche into account. Numerous case studies from psychotherapeutic practice illustrate the explanations given here.