In this book an internationally renowned scientist presents a radically new theory of the origin of life on Earth 4 billion years ago. Harold J. Morowitz postulates that the first step toward the origin of life was the spontaneous condensation of amphiphilic molecules to form vesicles (or protocells). This hypothesis provides a framework for reexamining the emergence of cellularity. Morowitz further proposes that core metabolic processes have not changed for some 3.8 billion years, so we can use a study of modern biochemistry to advance our knowledge about the chemical processes of the earliest protocells. Morowitz views origin-of-life issues from the perspective of certain constructs in the philosophy of science that provide guideposts to formulating and assessing hypotheses. This book presents a unique discussion among origin-of-life books on the relation between science and epistemology on the difficult problem of learning about the very distant past.