Wú Yún 吳筠 (d. 778), styled Zōng xuán xiān sheng 宗玄先生 (“Master of the Mysterious Lineage”) and posthumously Zhēn jié xiān sheng 貞節先生 (“Master Pure-Virtue”). A leading mid-Táng Daoist at the court of Táng Xuán zōng and Sù zōng. Native of Huá yīn 華陰 (Shǎnxī). A friend of Lǐ Bái 李白 — whose Daoist elevation owed much to Wú Yún’s recommendation — and author of a substantial corpus including KR5d0074 Zōng xuán xiān sheng wén jí 宗玄先生文集 (collected works), KR5d0075 Zōng xuán xiān sheng Xuán gāng lùn 宗玄先生玄綱論, and KR5d0077 Nán tǒng dà jūn nèi dān jiǔ zhāng jīng. Wú was one of the key Táng Daoists to expound a Chóng xuán 重玄-inflected metaphysics.