The origin of the talionic impulse may be seen in the real or fantasied attempt to undo an early childhood trauma by actively inflicting the experience on the original perpetrator. These impulses seem initially to demand immediate release; but as the individual matures, they are internalized and mastered, becoming adult superego functions, a personal morality. In the borderline patient, there is a failure to master the talionic impulse. Instead, the patient continually repeats the trauma. Often, because of identification with the aggressor, it is directed against the self. Such patients use psychotherapy not as a way of getting better, but of "getting back." Sometimes they channel these impulses into militant efforts on behalf of social causes. For therapy to be successful, the patient must master both the talionic impulse and castration anxiety. The author suggests that this mastery forms essential roots of adult morality.