and the skilled people at Unwin Hyman were steadfast and helpful at every point in the writing and publishing craft. To all the above people my sincerest thanks. I profited from their interest and assistance and the book has been greatly improved and enriched as a result of their efforts and helpful advice. Whatever errors and deficiencies that remain are not theirs, but mine.I wish to dedicate this book to my students who nurtured thinking about patterns of life and to my daughter Beverly Ann who is a constant inspiration and motivates thoughts about now and the future.