Forsberg, an antinuclear activist and defense policy expert who died in 2007, is most famous as a leader of the “nuclear freeze” campaign of the 1980s. As revealed by this remarkable book, the text of which comes from her 1997 doctoral dissertation, Forsberg was also a thoughtful theorist of peace studies and political change. War in world history, Forsberg claims, can be seen as “socially sanctioned large scale group violence,” a class of human behavior akin to human sacrifice, cannibalism, slavery, and lethal punishment. She observes that most people are revolted by these forms of violence, and so she delves deeply into psychology, anthropology, and history to see how and under what conditions societies reach moral judgments about certain kinds of violence. She believed that popular movements could transform people’s moral beliefs about war and weapons. Her thesis is a dazzling intellectual tour de force with a sobering conclusion: moral revolutions take many lifetimes to unfold, requiring centuries of dedication and struggle.