Liú Xīyuè 劉希岳 (zì Xiùfēng 秀峰, hào Tàixuán Lǎngrán zǐ 太玄朗然子, “Master Bright-as-Such of the Great Mystery”) was a Northern-Sòng Daoist active in the late tenth century. According to his autograph preface to Tàixuán Lǎngrán zǐ jìndào shī 太玄朗然子進道詩 KR5a0283 (DZ 271), dated Duāngǒng 端拱 wùzǐ (= 988), late in his life he had resided “in the Tōngxuán guàn 通玄觀 of Luòjīng 洛京 (Luòyáng)”; he writes that he was originally of well-to-do scholarly stock from the Zhāngshuǐ 漳水 region, that he passed the xiānggòng 鄉貢 (“provincial tribute”) examination, but withdrew to the Daoist gate. The preface emphasizes his synthesis of wàidān 外丹 doctrine (“by external alchemy I have penetrated the import of huǎnghū yǎomíng 恍惚杳冥”) and nèiqì 內氣 / tāixī 胎息 (“by inner qì I have illuminated the source of the embryonic-breath returning current”). The preface continues: “After labour of fewer than ten years, men marvelled that I do not age, though my count of years has already exceeded five 紀 [= sixty]” — implying he was already past the age of sixty in 988, hence a possible birth year ca. 925. The preface is dated to the late twelfth (winter) month of 988, in the Tōngxuán guàn. The work — thirty juéjù 絕句 in seven-character verse on alchemical and jìndào themes — was widely read in the twelfth century: it was inscribed in stone in 1131 (Sòng) and again in 1150 (Jīn). Note: TC and other sources also report Liú’s biography in the Jíxiān zhuàn 集仙傳 (43.25b) and Lìshì zhēnxiān tǐdào tōngjiàn 歷世真仙體道通鑑 50.1b, which give that “Liú became a Taoist in 988–989, at the age of sixty-four” — so the birth year is ca. 925. The Tōngxuán guàn was renamed Jìzhēn guàn 集真觀 in his honour by Emperor Zhēnzōng 真宗 following Liú’s xījiě 屍解 transfiguration.