This is one of the best books I have read all year. It differs from the standard "cool things in science" tract in that it focusses on what we don't know - where the mysteries are. In the end, that's often what's most interesting anyway...It is true that it is not always the easiest going, though I disagree with some of the other reviewers as to how hard it really is. If you truly paid attention in high school physics, biology, and chemistry, you should not have much trouble. The author does throw around terms like "reducing" or "organic" and expect you to understand them. Other terms, like "eukarote," are defined once - one must read attentively.If you can get past that, the clarity and comprehensiveness with which this book is written is breathtaking. I think I want to read it again.