In this new edition, I have added two additional chapters devoted to H8 approaches and to AI approaches, respectively. I have also added a chapter that, placed at the end of the book, briefly reviews the development of control, so forming something of a context for what has gone before. In addition to these major changes, I have reviewed and, where necessary, revised all the earlier material. In the spirit of the first edition, I have added ten additional diversionary ‘Interludes’ and of course taken the opportunity to update and enhance the references and suggestions for further reading. I very much hope that the resulting new edition is well placed to satisfy the aims of the first edition, which were as stated in the following section.