The Liu Cao 刘操

Liu Cao lived during the late Five Dynasties and early Northern Song Dynasty. He was from Guangling in the Yan region (now part of Hebei Province); according to other theories, he was either from Bohai (now Bin County, Shandong Province) or the Liao Dynasty. He also went by the given name Zhe, with the courtesy names Yuanying (or Xuanying, as "元" was sometimes substituted with "玄" due to naming taboos), and the literary name Haichanzi. He was commonly known as Liu Haichan in later generations. He had a keen interest in the doctrines of Huangdi (the Yellow Emperor) and Laozi, the foundational thought of Taoism.

He served under Liu Shouguang, the ruler of the Yan regime, as Prime Minister.

He encountered Lü Dongbin, who taught him various Taoist doctrines, including the principles of "quietness and inaction" for nurturing one’s nature and cultivating one’s life, as well as the art of "golden liquid and alchemical refinement" (a core practice of Taoist inner alchemy). He was a spiritual friend (friends bound by shared Taoist beliefs, beyond secular ties) with Zhang Wumeng, Zhong Fang, and Chen Xiyi (Chen Tuan). Liu Cao was skilled at composing poems and essays, and a collection of his poems was circulated in the world.

He abandoned his official post, retreated to Huashan Mountain to practice Taoism in seclusion, later moved to Zhongnan Mountain, and eventually withdrew to Phoenix Mountain in Daizhou for further seclusion.

In the sixth year of the Zhiyuan era of Emperor Shizu of the Yuan Dynasty (1269), he was posthumously conferred the title "Zhenjun of Bright Enlightenment and Vast Tao" (a revered title for Taoist immortals).

His works include Huanjin Pian (Treatise on Returning to Gold), Huandan Pomi Ge (Ode to Breaking Delusions about Alchemical Refinement), and Huangdi Yinfu Jing Jijie (Collected Annotations on the Yellow Emperor’s Hidden Talisman Classic). He is regarded as one of the "Five Northern Patriarchs" of the Quanzhen School (a major Taoist school in the Jin and Yuan dynasties).

Records of his life can be found scattered in works such as Shaanxi Tongzhi (Comprehensive Gazetteer of Shaanxi), Jifu Tongzhi (Comprehensive Gazetteer of the Capital Region), and Jianhu Ji (Collection of Jianhu).