Lǐ Zhì 李治 (1192–1279; CBDB id 29228), zì Rénqīng 仁卿, hào Jìngzhāi 敬齋, was a major JīnYuán mathematician and Confucian scholar. (The orthography of his name is sometimes given as 李冶 in modern reference works; the SòngYuán transmission and the Sìkù tíyào use 李治.) A jìnshì of the Jīn dynasty (Zhèngdà 6 = 1230); after the Jīn fall in 1234 he lived in retreat at the Yuánshì mountain in the Northern Hé-bĕi area. He is principally remembered today for the Cèyuán hǎijìng 測圓海鏡 (KR3p0024 in the Kanripo suànshù division) and the Yì gǔ yǎn duàn — pioneering algebraic works in the tiānyuán shù tradition. His one substantial bǐjì is the Jìngzhāi gǔjīn tǒu 敬齋古今黈 (KR3j0138) — originally 40 juàn, of which the SKQS recovers about one-fifth from the Yǒnglè dàdiǎn. The book is kǎozhèng-rich, with biàn (disputational) edge. Xuánzōng (the Yuán Shìzǔ Khubilai) summoned him to court but he declined.
The book-title gǔjīn tǒu uses the word tǒu 黈 — meaning “yellow silk ear-blocker” (used in imperial state regalia to symbolise “not hearing outside”) — from the Hàn shū Dōngfāng Shuò zhuàn “tǒu kuàng chōng ěr” (yellow-silk-ear-blocker stops the ear). The title is taken as “from ancient and modern, by means of inner concentration (and not outer listening)” — Lǐ’s account of his exhaustive devotion to ancient-and-modern study. Some transmission texts give the title as 古今難 (gǔjīn nán “ancient-and-modern difficulties”) — due to graph-similarity (tǒu vs. nán); the Qiánlóng emperor’s headnote to the SKQS recension explicitly addresses this and corrects it.