A critical biography of an influential seventeenth-century Welsh intellectual. Edward Lhwyd, an illegitimate son of a father ruined by the English Civil War, made his own way in the world, finally laying the foundation for modern Celtic studies. A competent botanist as a child, he spent his collegiate days at Oxford University in the Botanical Garden before being appointed the second keeper of the newly established Ashmolean Museum. This biography traces the development of his wide-ranging research interests beginning with botany and paleontology and leading into antiquarian studies and Celtic languages. Developing his own scientific method based on naturalistic observation, Lhwyd left an indelible mark on the history of science.