Instruct: Classify a review into positive or negative sentiment.
Query: Lack of credibility a serious flaw in such a book

Neither author evidently has any professional degree or apparent qualification to write a scientific book. I think that most readers would find them to be considerably more credible if they had such a degree, especially in view of the fact that Morgenthaler and Simms frequently foray onto (and beyond) the fringes of scientific knowledge. Such speculation would perhaps be tolerable if it were being espoused by someone who had a solid base of scientific training who had very sound reasons for conjecturing in this manner; it is difficult if not impossible for a reader who has no scientific background to judge whether or not the speculations of authors who have no scientific training are credible. The cover art and one of the fonts used in the text of this book can be best described as comical; they further detract from the credibility of the book.