Wasn't the twentieth century the most violent in history? In his extraordinary, epic book Steven Pinker shows us that this is wrong, telling the story of humanity in a completely new and unfamiliar way. From why cities make us safer to how books bring about peace, Pinker weaves together history, philosophy and science to examine why we are less likely to die at another's hand than ever before, how it happened and what it tells us about our very natures.