Zhīxuán 知玄 (811–883), with sobriquet Hòujué 後覺 and the imperial title Wùdá guóshī 悟達國師 (“National Preceptor Wùdá”), was a late-Tang Buddhist scholar-monk and one of the most celebrated court Buddhists of the Wǔzōng and Yìzōng reigns. Native of Hóngyǎ 洪雅 (Sìchuān). Lay surname Chén 陳; styled the Chén púsà 陳菩薩 (“Chén Bodhisattva”) in his youth.
Tonsured at age seven under Fǎ-tài 法泰 of Níng-yí-sì 寧夷寺; took full ordination under the Vinaya master Biàn-zhēn 辯貞 at Jìng-zhòng-sì 淨眾寺. He lectured on the Niè-pán jīng (Mahāparinirvāṇa-sūtra) at fourteen and was already known as the Chén pú-sà. Travelling to the capital, he was summoned by Wǔ-zōng to debate with the Daoists; his yǒu-yán fēng-lì 出言鋒利 (“razor-sharp speech”) in the imperial debate is recorded in his biography. He subsequently lectured in the imperial palace and was granted the zǐ jiā-shā 紫袈裟 (purple robe) and titled Sān-jiào shǒu-zuò 三教首座 (“Senior Officer of the Three Teachings”). The emperor founded Fǎ-qián-sì 法乾寺 on the site of an old residence and installed Zhī-xuán there. He later sought leave to return to Sì-chuān and resided at Dān-jǐng-shān 丹景山 in Péng-zhōu.
Died in Zhōng-hé 3 (883), aged seventy-three (54 years in the saṃgha). His extant works include the Cí-bēi shuǐ-chàn fǎ 慈悲水懺法 (KR6k0199, T1910) — the Repentance Liturgy of the Compassionate Water — composed after his celebrated encounter with the arhat Jiā-nuò-jiā 迦諾迦 (Kanaka), which is preserved in the Sòng gāo-sēng zhuàn j. 6 hagiography; the Shèng-mán jīng shū 勝鬘經疏 (commentary on the Śrīmālādevī-sūtra); the Bō-ruò xīn-jīng shū 般若心經疏 (commentary on the Heart Sūtra); and the Jīn-gāng-jīng shū 金剛經疏 (commentary on the Vajracchedikā).
Sources: Sòng gāosēng zhuàn j. 6 (T2061, 743b04); Yínián lù 161; Fóguāng 4113; DILA Buddhist Person Authority A000753.