Someone afflicted by mental illness is neurotic if he sees his symptoms as symptoms and psychotic if does not. A neurosis is therefore an 'ego-dystonic' mental illness, meaning that the viewpoint embodied in one's symptoms is not the viewpoint of the ego of the afflicted party. And a psychosis is therefore an 'ego-syntonic' illness, meaning that the viewpoint embodied in the symptoms coincides with that of the afflicted party's ego. Whereas ego-syntonic illnesses are unqualifiedly debilitating, ego-dystonic are sometimes adaptive and, within limits, may enhance the subject's ability to deploy his abilities. In this lecture, it is explained why this is so. An Author's Republic audio production.