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...