Essential Subtleties on the Silver Sea presents the first translation into English of the complete Yin-hai jing-wei, a classic fifteenth-century text on Chinese ophthalmology. As one of the few original manuscripts on traditional Chinese medicine translated into a Western language, this work offers an unprecedented view of the practice of medicine, and specifically eye care, in premodern China. Not one reference to acupuncture can be found here. Instead, the most commonly advocated mode of therapy employs a wide variety of herbal, mineral, and animal substances. There is also ample evidence of the importance of surgical interventions in eye treatment and of the influence of foreign (mainly Indian) health-care practices on the development of Chinese ophthalmology. As a source document for comparative studies of Chinese and Western medicine, of the image and reality of Chinese medicine, and of numerous other issues in the history of medicine and Chinese thought, the Yin-hai jing-wei has no equal in the Western world.