For the first time in a popular science form, Professor Wiseman's book substantiates the problems of medical and psychological control in chess sports. The changed states of consciousness leading to the loss of the won game are described, as well as other chess paradoxes. Electrophysiological studies of the brain during the game, the influence of doping and hypnosis in chess, problems of biorhythms and age are considered. Psychohygienic and psychotherapeutic recommendations are given. Other chess issues from medical and psychological positions are also discussed.