More people today report feeling anxious than ever before—even while living in relatively safe and prosperous modern societies. Almost one in five people experiences an anxiety disorder each year, and more than a quarter of the population admits to an anxiety condition at some point in their lives. Here Allan V. Horwitz, a sociologist of mental illness and mental health, narrates how this condition has been experienced, understood, and treated through the ages—from Hippocrates, through Freud, to today.Anxiety is rooted in an ancient part of the brain, and our ability to be anxious is inherited from species far more ancient than humans. Anxiety is often adaptive: it enables us to respond to threats. But when normal fear yields to what psychiatry categorizes as anxiety disorders, it becomes maladaptive. As Horwitz explores the history and multiple identities of anxiety—melancholia, nerves, neuroses, phobias, and so on—it becomes clear that every age has...