Two Victorian Era movements affected American legal thought: Darwinian natural selection and marginalist economics. Darwinism emphasized instinct and random selection. Marginalism emphasized rational choice. Notwithstanding profound differences in the assumptions and methodologies of these movements, legal theory accommodated both. It is not often that a book offers a broad intellectual history of how the social sciences influence the development of law and legal thought. However, this is exactly what Professor Hovenkamp does in his latest book about the intellectual history of American law. Overall, this book would be a very useful complement to courses on comparative law, antitrust, and law and economics courses.