A collection of essays on various scientific subjects. Dr. Asimov was a chemist, I believe, and the first half of this book is devoted to chemical issues. I confess, chemistry is my most hated science. I stumbled through the pages very slowly, thinking this would probably be a two-star book (worthy but dull) and then chemistry ended and he started writing about maths and biology and history, all of which I find infinitely more tolerable than messing around with the structure of molecules. The maths section was the most enjoyable... it hauled the whole thing up a star.