It was long believed that evolutionary theories received an almost universally cold reception in British natural history circles in the first half of the nineteenth century. However, a relatively recently serious doubt has been cast on this assumption. This book shows that Edinburgh in the late 1820s and early 1830s was witness to a ferment of radical new ideas on the natural world, including speculation on the origin and evolution of life, at just the time when Charles Darwin was a student in the city. Those who were students in Edinburgh at the time could have hardly avoided coming into contact with these new ideas. This book is the first major study of what was probably the most important centre or pre-Darwinian evolutionary thought in the British Isles. It sheds new light on the genesis and development of one of the most important scientific theories in the history of western thought.