Book excerpt: This book examines the relationship between humans and nature that evolved in medieval Europe over the course of a millennium. From the beginning, people lived in nature and discovered things about it. Ancient societies bequeathed to the Middle Ages both the Bible and a pagan conception of natural history. These conflicting legacies shaped medieval European ideas about the natural order and what economic, moral, and biological lessons it might teach. This book analyzes five themes found in medieval views of nature - grafting, breeding mules, original sin, property rights, and disaster - to understand what some medieval people found in nature and what their assumptions and beliefs kept them from seeing.