Wu Jun (?-778 AD), alias Zhenjie, was a famous Daoist of the Tang dynasty (618-907). He was from Huayin (today's Huayin County of Shaanxi province). It is also said he was from Luzhong (in today's Shandong province). Wu studied the Confucian classics when he was young and he was good at writing essays too. Being noble and unsullied, he did not drift in life. After he failed the highest imperial examination, he went to Mount Songshan to study Dao with the Daoist Pan Shizheng as his teacher. During the Kaiyuan years (713-714 AD), Wu went on a journey to Jin Ling and visited Mt Mao. Later he traveled to Mount Tai and went to see the great sea. At the time he went to parties with men of letters and his poems written at the parties were widely read in the capital. Emperor Xuanzong heard about him and sent the messenger for him. The emperor was pleased to talk with him and asked him to wait for the imperial decree for him to be a member of the Imperial Academy. As the emperor asked him about Dao, Wu replied, "When it comes to the essence of Dao, there is nothing beyond the Book of Dao and its Virtue. Much that has been discussed about it is but a waste of paper." The emperor asked him about the cultivation of Dao and immortality, and Wu answered, "That was the business of the ordinary people and immortality could only be accomplished by persistent pursuit of constant efforts. It was not fit for the ruler." During the Tianbao years (742-756 AD) when Li Linfu and Yang Guozhong were in office, Wu realized that there would be a great disorder throughout the empire, and he requested to go back into the mountains. Later he took a journey to Kuaiji, where Wu corresponded with Li Bai and other men of letters by writing poems, living free and unfettered in seclusion. In the 13th year of Dali in Daizong's time (778 AD), Wu died in a Daoist temple in Xuancheng. Wu's followers conferred him the title of Gentleman Zongxuan. His works are as follows: Treatise on the Mysterious Matrix ( 《玄綱論》 Xuangang Lun ), On the Possibility of Learning to be an Immortal ( 《神仙可學論》 Shenxian Kexue Lun ), On the Eye of the Mind ( 《心目論》 Xinmu Lun ), On the Possibility of Consolidating the Human Form and Spirit ( 《神形可固論》 Shengxing Kegu Lun ), etc.