Mirror of Beryl is a detailed account of the origins and history of medicine in Tibet through the end of the seventeenth century. Its author, Desi Sangyé Gyatso (1653–1705), was the heart disciple and political successor of the Great Fifth Dalai Lama and the author of several highly regarded works on Tibetan medicine, including Blue Beryl, a commentary on the foundational text on Tibetan medical practice, Four Tantras. In the present historical introduction, Sangyé Gyatso traces the sources of influence on Tibetan medicine to classical India, China, Central Asia, and beyond and shows how it developed in Tibet through royal patronage and the establishment of practice lineages. He provides an extensive bibliography of works on medicine, many of which are no longer extant; he provides life details on many central figures, such as Yuthok Yönten Gyatso, and critiques the contribution of another influential figure in the fascinating history of Tibetan medicine.