A study of one hundred patients who had undergone major surgery indicates that man needs to establish beliefs explaining events that happen to him. The more serious the disease (threat), the more urgently does he need to explain it in order to preserve his sense of mastery and emotional integrity. The selection of any specific belief explaining the threat is a function of the character structure of the patient, but the most striking finding of this study is the prevalence of beliefs that personal relationships can be sufficiently injurious to cause severe illness.