Ego boundary formation occupies a contested yet indispensable position across the depth-psychological corpus. Freud establishes the foundational problematic in Civilization and Its Discontents, tracing how the nascent ego learns to discriminate ‘inside’ from ‘outside’ through the painful discipline of the pleasure principle yielding to the reality principle — a process rooted in somatic experience and the loss of the mother’s breast. Neumann extends this developmental arc mythologically, arguing that boundary formation is the precondition of consciousness itself, the ego wresting differentiated selfhood from the undifferentiated pleroma of the uroboros. Winnicott, approaching from object-relations, frames the same achievement in terms of a ‘facilitating environment’ within which the true self consolidates its isolation — a protective boundary whose violation produces psychotic anxiety rather than developmental advance. Hillman, characteristically, radicalizes the critique: he identifies boundary-making with senex-consciousness, the Saturnine psychic force that organizes inner life through division, ownership, and the sacred temenos, insisting that boundaries are ontological as much as psychological necessities. Samuels surveys the developmental Jungian school, documenting how theorists such as Fordham, Gordon, and Strauss treat boundary formation as the ego’s primary task against the self’s pull toward fusion. The somatic tradition represented by Ogden situates boundary formation in the body itself, making it a procedural achievement of early attachment rather than a purely mental event. What unifies these positions, despite their divergence, is the recognition that without a formed boundary there can be no self, no symbol, and no relatedness — only undifferentiated merger.