I was delighted to see this book. As a chemist, I have always felt my own particular discipline to be under-represented in the thriving canon of popular science literature, and hoped this might make a small step toward restoring the balance. I was not disappointed. Most people are aware of our dependence, and indeed that of all animals, on oxygen for burning our food to provide us with energy and life, and of the importance of plant photosynthesis in maintaining the atmospheric concentration of the gas. But oxygen is an extremely reactive element, and readily combines with just about anything with which it comes into contact. How then did Earth come to have such an apparently stable atmosphere, which along with all the other characteristics and conditions, makes our planet seem so finely tuned to support active life? This is the question the author aims to answer. He takes us on a journey that begins in extreme ocean depths, where life may have started more than three billion years ago, without the benefits of oxygen. We continue through the eons of geological time, when cyanobacteria evolved to pollute the primordial atmosphere with what was initially a gas highly toxic to primitive organisms. We observe the rises and falls of oxygen concentration during different geological periods and its interactions with the rocks, the oceans and the creatures that evolved not just to cope with it but to thrive on it. To tell this story, Professor Canfield draws on his own experiences in the field, and those of colleagues, and explains the detailed research into the geological evidence that has led to our still growing understanding of these particular processes in Earth’s history. This is where the chemistry comes in, involving the reactions of oxygen with many other elements, such as carbon, hydrogen, sulphur, phosphorus, iron, manganese and molybdenum. This is not easy stuff, and the author is well aware of the subject’s difficulties, but he does not shrink from them or talk down to his readers. He describes the often complex chemical reactions with considerable skill and the use of analogy where appropriate, and in just sufficient detail for them to be accessible to those with at least some background in chemistry. For those with a deeper understanding, he has added sixteen pages of further notes which include relevant chemical equations. Rather than a simple history of life on earth and its interaction with oxygen, this book contains a lot of serious science. It tells a fascinating story that will appeal to all who are interested in how the earth came to be as it is. Chemists will love it.