The line connecting ego-center with Self-center represents the ego-Self axis—the vital connecting link between ego and Self that ensures the integrity of the ego.
Edinger establishes the ego-Self axis as the foundational structural concept in his developmental psychology, defining it diagrammatically as the connecting line that preserves ego integrity across successive stages of separation.
, Ego and Archetype: Individuation and the Religious Function of the Psyche, 1972thesis