Liú Zǐchéng 劉子澄, zì Qīngshū 清叔, hào Yùyuān zǐ 玉淵子 (“Master of the Jade Abyss”), was a Southern-Sòng official and Daoist sympathiser, active in the mid-thirteenth century. He held minor regional posts in Húnán: at the age of 28, in connection with frontier troubles, he was demoted to Chōnglíng dào 舂陵道 in Yuèyáng 岳陽; later he was recalled north and stationed at Jiānglíng 江陵 (frontier-quarters administrator), then at cān Jiāngkǔn mùxià 參江閫幕下. According to his own preface (1251) to [[KR5a0291|Xiāntiān jīndān dàdào xuán’ào kǒujué 先天金丹大道玄奧口訣]] (DZ 279), he encountered a qiáoyǐn 樵隱 (“woodcutter-recluse”) at the Yǎyín 雅吟 pavilion who first taught him the jīndān 金丹 essentials in song form; later, while quartered with friends at Jiǔyí 九嶷, he came to grasp the alchemical method on his own; finally, the gentleman Huò 霍 of Pílíng 毗陵 [Huò Jìzhī 霍濟之] arrived with his alchemical formula in hand, which Liú recognised as identical to what he had learned at Yuèyáng. Liú’s preface, signed Chúnyòu xīnhài lìxià jírì Yùyuān zǐ Liú Zǐchéng Qīngshū xù 淳祐辛亥立夏吉日玉淵子劉子澄清叔序 (1251), is the most informative single document on the textual history of the Xuán’ào kǒujué. CBD 5, 3919.