Thomas Jefferson once wrote to a friend that politics was his "duty" but natural history was his "passion." As this book shows, he was always a man for whom nature was important. With his devotion to detailed knowledge, precise calculation, and rational enquiry, natural history related to everything he did, as a farmer, as a philosopher, and as a citizen. For all his gifts in philosophy and politics and his fascination with the American West, he was never more happy than at home at Monticello, riding across the fields and experimenting with new crops. The great wonder is that, in addition to his public life, he had time to be one of American's first serious students of, among other things, fossils, botany, climate, geology, and anthropology. Author, Keith Thomson was a visiting fellow at the Thomas Jefferson Foundation's Robert H. Smith International Center for Jefferson Studies in 2007. He is professor emeritus of natural history at Yale University and senior research fellow of the American Philosophical Society. Author of twelve other books on evolution, paleontology, and the history of science, he was previously professor and dean at Yale, president of the Academy of Natural Sciences in Philadelphia, and university scientist-in-residence at the New School for Social Research.