I do reserve the right to challenge what I don't use. Book's preface is one thing to start with. I never read it. If the title of the book is self explanatory, why would you need a preface, specially while reading a technology book? I prefer to surf through the chapters instead, than to read its' preface. It contributes no useful purpose to the content of the book. Something similar to an unnecessary chain of management command in any organization. I recently watched Andy Hertzfeld's interview on PBS. The guy is a programming legend. "The best size team comprises of just one person" was his comment on the discussion around an ideal size of any team. He did quote Albert Einstein stressing the need of removing the communication overheads. We continue to use them for the sake of tradional heirarchy and are afraid to challenge its presence. Something similar to a preface in the book.