The book Wai tai mi yao fang (Arcane medical essentials from the Imperial Library) records 69 medical classics published before the Tang dynasty (618–907) and contains 6,900 entries. Parts of original works that no longer exist thus are preserved in this compilation. It lists many diseases and methods of diagnosis, records methods of compounding medicines, and discusses acupuncture, bathing, medical exercises, artificial emergency aid, and other topics. Compiled by Wang Tao (670−755), the work represents an outstanding contribution to the preservation of traditional medical classics and summarizes the medical achievements of traditional Chinese medicine before the Tang dynasty. This encyclopedic medical work appeared after the publication of Sun zhen ren bei ji qian jin yao fang (Daoist Sun's invaluable prescriptions for ready reference), a general book of medicine by Sun Simiao (581−682).