Dear reader, Having lived in Uganda and spoken with people who escaped from the savagery of the brutal dictators Milton Obote and Idi Amin, having heard stories of my father’s childhood as a Jew running through Nazi occupied France, and reading past and present-day accounts of genocide, I am familiar with the horrors of evil. I have also been a student of human nature, trained as a scientist. These experiences have propelled me to study the causes of evil, attempt to make some progress in explaining it to myself, and hopefully to you. There is a great urgency to understanding this problem. None of us can afford to passively watch millions of individuals lose their homes, children, and lives as a result of malice. Sloth is asin, especially when we live in a world where cultures of evil can so easily erupt. Iam also familiar with and deeply moved by human kindness, our capacity to reach out and help strangers. When my father was in a boarding school in the south of France, hiding from the Nazis, a little girl approached him and asked if he was Jewish. My father, conditioned by his parents to deny his background, said no. The girl, sensing doubt, said “Well, if you are Jewish, you should know that the director of the school is handing Jewish children over to the Nazis.” My father promptly called his parents who picked him up, moved him to another village and school, and survived to tell the story. This little girl expressed one of our species’ signature capacities: the ability to show compassion for another person, even if their beliefs and desires are different. In preparation for writing this book, I read transcripts and descriptions of thousands of horrific events, listened to personal stories of survivors from financial ruin and war, worked with abused children who were crucified by unfit parents, and watched both fictional films and documentaries that portrayed psychopaths, dictators of totalitarian regimes, and their hapless victims. As one often does in these