This book investigates the profound and often overlooked influence of sibling relationships on the development of psychopathology. The authors argue that early experiences with siblings are central to shaping unconscious fantasies that can lead to mental illness, and that understanding these dynamics is crucial for effective psychoanalytic treatment. Drawing on extensive case material, Gabriele Ast and Vamik D. Volkan integrate traditional psychoanalytic concepts with contemporary theoretical advancements to explore complex themes such as womb fantasies, claustrophobia, fears of pregnancy, murderous rage, animal symbolism, and specific neuroses related to holidays like Christmas and Easter, as well as the impact of twinship and sibling identification.

The book is presented as a significant contribution to psychoanalytic literature, emphasizing the underappreciated role of siblings in emotional development and psychopathology. Reviewers highlight the authors' central contention that sibling experiences shape pathogenic unconscious fantasies, which are essential to address in treatment. The use of case material is noted as exemplary in illustrating theoretical points, blending traditional psychoanalysis with newer theoretical innovations. The work is positioned as a valuable resource for understanding the complex interplay between sibling relationships and mental health.