Liú Zhījǐ 劉知幾 (661–721), zì Zǐxuán 子玄 (later regularly written 子元 to avoid the Kāngxī taboo on 玄). Native of Péngchéng 彭城 (modern Xúzhōu, Jiāngsū), from a family of historian-officials — his elder brother Liú Zhīróu 劉知柔 reached high office, and four of his own sons made names for themselves in historical writing, the second son 劉餗 (Liú Sù) being the principal continuator of his father’s Shǐtōng 史通.
Promoted jìnshì in Yǒngchūn 1 (682) at twenty, Liú served as Sheriff of Huòjiā 獲嘉 (Hénán) before being summoned to the History Office under Wǔ Zétiān, in which he served continuously from 702 onwards through the Zhōngzōng, Ruìzōng, and early Xuánzōng reigns. He held the substantive positions of Drafter at the Phoenix Pavilion (Fènggé shèrén 鳳閣舍人), Crown Prince’s Coachman (Tàizǐ shuàigèng lìng 太子率更令), Imperial Library Director (Mìshū jiān 祕書監), Crown Prince’s Senior Attendant (Tàizǐ zuǒ shùzǐ 太子左庶子), Chóngwén Hall Academician, and finally Standing Attendant (Zuǒ sǎnqí chángshì 左散騎常侍). After being implicated in the affair of his son Liú Yìng’s 劉貺 case, he was demoted to Deputy Prefect of Ānzhōu 安州 in 721, where he died in office.
Within the History Office Liú participated in the compilation of the veritable records of Wǔ Zétiān (Zétiān shílù 則天實錄), Zhōngzōng (Zhōngzōng shílù 中宗實錄), and Ruìzōng (Ruìzōng shílù 睿宗實錄), and in revisions to the Tángshū 唐書 (then in progress) and the official “national history” (guóshǐ 國史). Frustrated by what he diagnosed as the structural pathologies of collective imperial historiography, in 708 he submitted to Xiāo Zhìzhōng 蕭至忠 a famous letter of resignation laying out five specific complaints (preserved as Shǐtōng Wàipiān 13). His magnum opus the KR2o0001 Shǐtōng 史通 (Inner Chapters completed 710; Outer Chapters completed posthumously by Liú Sù in 722) is the earliest systematic treatise on historiography in Chinese — and indeed in any language — and the model for Zhāng Xuéchéng’s KR2o0025 Wénshǐ tōngyì 文史通義 a millennium later.
Liú was buried in Péngchéng. The Jiù Tángshū j. 102 and Xīn Tángshū j. 132 carry his biography. CBDB id 31723 confirms 661–721 as his lifedates.