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 microcosms of the societies in which they exist, and by examining them in detail, we can learn about society as a whole. Gilligan suggests treating violence as a public health problem. He advocates initiating radical social and economic change to attack the root causes of violence, focusing on those at increased risk of becoming violent, and 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 twentieth century was steeped in violence. If we attempt 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.