On the basis of thermodynamic considerations and the Earth’s historical processes, this book argues the physical inevitability of life’s generation and evolution, i.e., Why did life generate? Why does life evolve? Following an introduction to the problem, the hypothesis “Darwinian Evolution of Molecules” is proposed, which explains how, when, and where life was instigated through successive chemical reactions and the survival of selected molecules. The individual processes described are all scientifically reasonable, being verifiable by experiment. The hypothesis is supported by extensive reference to the scientific literature published in academic journals, including some experimental reports from the author’s own research group. The readers of this book will learn that the decreasing temperature of the early Earth led to a reduction in its entropy, inducing the Earth’s materials to order, which entailed ordering of the light elements as organic molecules with subsequent further ordering (i.e., evolution) to systems that can be considered alive (i.e., life). Researchers and students, as well as the non-academic audience, interested in the interdisciplinary problem of the origin of life will find suggestions and possible approaches to the scientific and conceptual problems they may be facing. Hiromoto Nakazawa is an emeritus fellow at the National Institute for Materials Science, Japan, and a fellow of the Japan Geoscience Union. He is also a former chairman of The Clay Science Society of Japan (2001–2002). He devoted most of his research time to X-ray crystallography while at the National Institute for Research in Inorganic Materials (NIRIM), Japan. As a materials scientist, he has been awarded the Crystallographic Society of Japan Prize (1978) for the identification and study of new superstructures of iron sulfides using X-ray diffraction and high-resolution electron microscopy. He was also awarded the Medal of Honor with Purple Ribbon as well as several other prizes for his invention of the scanning X-ray microscope using the X-ray guide tube (2000). His curiosity regarding the origin of life from his student days brought him to the study of clay minerals as materials at the interface between the inorganic and organic realms during his tenure as a managing researcher at NIRIM (1985–2000). While a professor at Tohoku University, Japan (2001), he commenced his experimental studies of the origin of life together with his students and subsequently proposed a new scenario for the origin of life on the Earth based on their recent results (2006, 2014). In 2011, he received the Order of the Sacred Treasure, Gold Rays with Neck Ribbon.