The idea of the Devil has proved to be one of the most powerful and fascinating that the human mind has come up with. People everywhere find the idea plausible and powerful. Its changes and the uses to which it has been put tell us much about wider changes in thinking, culture and society. And we can be sure he will be with us for a long time to come. This new book is a highly original philosophical and historical analysis of this key figure in all cultures. / The Devil is an idea or concept - and as such has a history. The essential and distinctive idea is not that he is the source of evil but that he is malevolent. He knowingly wills the bad. Other key notions are that he is a spiritual being, of immense power, and that he is a person or entity.