This book has been most difficult to write for many reasons. Preeminent among them is that it has always been a book in process. I have not learned about human evil I am learning. In fact, i am just beginning to learn. One chapter is entitled 'toward a psychology of evil' precisely because we do not yet have a body of scientific knowledge about evil sufficient to be dignified by calling it a psychology. So let me add another note of caution: do not regard anything written here as the last word. Indeed, the purpose of the book is to lead us to dissatisfaction with our current state of ignorance of the subject.