Qián Yǐ 錢乙 (1032–1113, zì Zhòngyáng 仲陽), Northern-Sòng physician of Yùnzhōu 鄆州 (modern Dōngpíng 東平, Shāndōng). Foundational figure of post-classical Chinese paediatrics. Trained originally as a folk-paediatrician, recognised by the imperial court after he successfully treated a niece of the Yáng family; appointed to a post in the Tàiyījú 太醫局 (Imperial Medical Bureau). Died at 82, the longest-lived of the canonical Sòng medical authorities. His paediatric thought — preserved in the Xiǎoér yàozhèng zhíjué 小兒藥證直訣 (KR3ej020) compiled by his disciple Yán Xiàozhōng 閻孝忠 in 1119 — is the founding synthesis of Chinese paediatric medicine: the doctrine of paediatric chúnyáng 純陽 (pure-yang) constitution, the systematic application of the Five Phases / zàngfǔ schema to paediatric pathology (with characteristic adjustments — gān 肝 always over-vigorous, pí 脾 always weak, shèn 腎 always deficient), and the canonical prescriptions Liùwèi dìhuáng wán 六味地黃丸, Dǎochì sǎn 導赤散, Xièbái sǎn 瀉白散, Yìhuáng sǎn 益黃散, Sìjūnzǐ tāng 四君子湯 in its paediatric form, and the dozens of others which became the foundation of subsequent paediatric prescription practice. He is the universally recognised yàozǔ 藥祖 (medicine-progenitor) of the Chinese paediatric tradition. The Tàipíng huìmín héjì jú fāng 太平惠民和劑局方 and the entire post-Sòng paediatric corpus depend on his work. His biography appears in Sòngshǐ 462.