In preparing the series, I initially wrote careful studies for each of the topics to be covered. These served as the core material from which the television scripts were developed. From the initial studies, modified with the scripts, I then wrote the book. In many cases, the book goes further than the ideas or facts covered in the television programs.

Fortunately, there is no need to restrict a chapter to what can be read in an hour, or at least not yet. There are also photographs here, but to illustrate the story.

[Excerpt from the text of the preface]