Book excerpt: Three grand themes characterized the twentieth century: crises on a scale that outstripped any in human history, revolutionary ideology and action that brought social and political transformation on a global scale, and new technologies breathtaking in their pace and innovation. This book explores the contradictions, commonalties, and varieties of human experience. Thematic chapters deal with issues such as modernization, imperialism, social revolutions, fascism, feminism, fundamentalism, war and peace, science, population, and economic inequality.