This fascinating discussion of modern demonology focuses on our ability to differentiate the physical world, with its mechanical laws, from the inherently less predictable psychological realm of thoughts and beliefs. McGrath points out that this ability was a hard-won historical development, and today must be learned in childhood through education. Because of this historical background and our rich fantasy life in childhood, each of us unconsciously suspects, or fears, that supernatural forces may break through the borders of our everyday commonsense order at any time. Indeed, at times of...