《旧唐书·列传·卷六十八》
天宝初年，玄宗崇尚奉行道教，下诏书求得精通庄子、老子、文子、刘子四人的学者。
天宝初，玄宗崇奉道教，下诏求明庄、老、文、列四子之学者。
At the beginning of the Tianbao reign, Xuanzong advocated the Daoist religion, and issued an imperial edict seeking scholars who were well-versed in the works of Zhuangzi, Laozi, Wensi, and Liuzi.