In this controversial and compassionate book, the distinguished American psychiatrist James Gilligan proposes a radically new way of thinking about violence and how to prevent it. Violence is most often addressed in moral and legal terms: 'How evil is this action, and how much punishment does it deserve?'. Unfortunately, this way of thinking, the basis for our legal and political institutions, does nothing to shed light on the causes of violence. Violent criminals have been Gilligan's teachers and he has been their student. Prisons are a relatively 'pure' culture of violent behaviour, and are microcosms of the societies in which they exist. By examining them in detail, we can learn about society as a whole. Gilligan suggests treating violence as a public health problem. He advocates, firstly, initiating radical social and economic change to attack the root causes of violence; secondly, focusing on those at increased risk of becoming violent; thirdly, dealing with those who are already violent as if they were in quarantine rather than in constraint for their punishment and for society's revenge. The 20th century was steeped in violence. If we try to understand the violence of individuals, we may come to prevent the collective violence that threatens our future far more than all the individual crimes put together.