  Ge Hong was the first to systematically describe the history and theory of Daoist immortality techniques such as “preserving unity” (shou yi 守一), circulating energy (xing qi 行氣), “guiding and pulling” (dao yin), and sexual longevity techniques (fang zhong房中, Baopuzi neipian, ch. 2; Lai Chi-tim 1998, 203-204). But his accounts of these techniques clearly reflect an interest in self-cultivation according to broadly Confucian principles. For example, he considered moral self-cultivation a precondition for the search for immortality; self-cultivation included such Confucian virtues as benevolence (ren), trustworthiness (xin), loyalty (zhong) and filiality (xiao). Ge Hong criticized Daoist “pure conversation” (qing tan) and emphasized the importance of both moral virtue and Daoist study. His specifically Daoist writings emphasize the importance of both “mystery” (xuan 玄) and emptiness (xu 虛), and all-embracing unity, which the Daoist must actively preserve by meditation practices, techniques of “preserving the essence” (bao jing 保精) and consuming medicinal herbs (fu yao 服藥).