Ko Hung (fourth century A.D.), Chinese Taoist philosopher, also known as the Master Who Embraced Simplicity (Pao-p’u tzu). Ko Hung is a pivotal figure in the development of Taoism. His major work, the Pao-p’u tzu, emphasizes the importance of moral cultivation as a necessary step to spiritual liberation. In this Ko is often said to have synthesized Confucian concerns with Taoist aspirations. He champions the use of special drugs that would purify the body and spirit in the quest for Taoist transcendence. A firm believer in the existence of immortals (hsien) and the possibility of joining the ranks of the perfected, Ko experimented with different methods that fall under the rubric of ‘external alchemy’ (wai-tan), which merits attention also in the history of Chinese science. See also HSIEN. A.K.L.C.