Engel in his introductory remarks to a discussion of Neoplastic Disease and Psychological Processes comments on the deficiencies in our knowledge of the relation of the psychic to the somatic. In fifteen volumes of Psychosomatic Medicine, eighty percent of the papers have been devoted to a relatively small number of clinical syndromes, and Engel believes that the selection of these few diseases is frequently made 'impressionistically, silently, and on the basis of unacknowledged bias'. We know but little of the physiology of such psychological processes as conversion reactions, the effects of maternal deprivation, object relationships,