David Schwartzman's book is a masterpiece of geological analysis that probes the role of temperature change in the history of Earth and Life. He makes a convincing case that the biological enhancement of weathering by organisms (mostly microbes and plants) has led to overall decrease in Earth surface temperatures, something of a paradox considering that the sun has grown hotter over that same interval. It is no wonder that thermophilic microbes are among the oldest types of creatures known. They evolved when the earth was hot and they still like it that way, living today in hot springs and other thermal areas. This book considers thermal constraints on evolution of complex life, scrutinizes evidence for ancient glaciation, and most importantly considers how plants and soil microbes suck up carbon dioxide (thus cooling the climate) by decomposing certain types of silicate rocks. A must read for those interested in the evolution of life and environment through time!