This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book explores the John Bowlby uses a discussion of Darwin’s theory of emotions as a springboard for critical examination of the purposes of psychological classification. It presents Bowlby’s reflections on the psychology of evacuation, with much of contemporary relevance, for instance in work with child refugees. The book discusses Bowlby’s early attempt to wrestle with Sigmund Freud’s account of guilt and anxiety. It examines the psychoanalytic theory and political philosophy in reflecting on the meaning of conflict and the ways in which potential conflicts can be best regulated in the clinical and political spheres. A commonly held position in the psychoanalytic theory of Bowlby’s day was that mental health symptoms are ultimately caused by innate drives like sexuality and aggression. By contrast, Bowlby emphasised the significance of actual childhood experiences in shaping mental health.