a fundamental, basic sense of stability and reality of one’s own existence and the world around them. This is a kind of psychic foundation, an unshakable confidence that “I am real, the world is real, and there is a clear border between us.” Key aspects:1) Strong self: A clear and stable sense of self, boundaries, and identity.2) The reality of the world: The belief that the external world exists objectively and reliably.3) Interconnection: Confidence in the possibility of authentic and predictable contact with other people.This is the opposite of ontological uncertainty (see Ontological uncertainty in Chapter 1.7 Key Psychological Concepts in Personality Psychology). Such confidence is formed in early childhood through secure attachment and is the basis of mental health, which is expressed in a stable, but at the same time plastic (i.e., adaptive) personality.