This new study, part of Professor Robert Stoller’s well-known, continuing work on sex and gender identity, is especially concerned with the psychological forces that contribute to sexual excitement in men and women. The author looks at sexual aberrations in order to learn what they can tell us about the dynamics of “normal” sexual development. He shows that perversions are different from other aberrations in that the dominant force in perversion is hostility directed in reality or in fantasy toward one’s sex objects. And he shows through fascinating examples and case material how childhood frustrations, traumas, and conflicts are gradually transformed into sexual excitement by means of fantasies. In a daydream, pornography, or a ritualized pattern of sex practice, a scenario is created in which are hidden remnants of the earlier painful experiences, now redone to make a triumph out of the trauma: the victim becomes the victor. It has been noted that men practice a wider variety of perversions than women. Professor Stoller suggests that men’s greater propensity to perversion in our society is related to the mother-daughter infant symbiosis—an intimate merging in which the infant does not distinguish its own boundaries as separate from its mother’s. If that intimacy is too intense or too prolonged, the infant boy’s sense of oneness with femaleness and femininity persists into the later months when masculinity begins to develop. A flawed sense of maleness can then result, thereafter threatening the development and expression of a stable masculinity. In contrast, should a comparable intense symbiosis develop between a mother and her infant daughter, the sense of merging with mother will only augment the girl’s future femininity, although it may result in other kinds of complications.