Using the Kleinian concept of projective identification, with special reference to intrusive identification with internal objects, this work examines claustrophobic phenomena and their relation to the treatment of borderline and adolescent patients.  Founding his theory as always on clinical discoveries, Meltzer discovered that not only the uterus, but also other spaces of the internal mother figure, are susceptible to becoming a “maternal claustrum”, each giving rise to distinct pathologies that pre-empt the patient establishing a true relationship with either himself or others. The book pairs with The Apprehension of Beauty as a radical post-Kleinian revision of psychoanalytic theory, and concludes with a literary study of Macbeth by Meg Harris Williams illustrating the distinction between the equivocation of the Claustrum and the ambiguity of poetry.