The fact that there is a reciprocal relation between mental states and bodily conditions, acting both for good and ill, is nothing new in human experience. Even among the most crude and unobserving, traditions and incidents have given witness to this knowledge. For centuries stories of the hair turning white during the night on account of fright or sorrow, the cause and cure of diseases through emotional disturbances, and death, usually directly by apoplexy, caused by anger, grief, or joy, have been current and generally accepted. On the other hand, irritability and moroseness caused by disordered organs of digestion, change of acumen or morals due to.
