Southern-Sòng physician-Daoist (1108–1190) of the Lú Shān 廬山 region; zì Zǐxū 紫虛, hào Xīyuán Lǎorén 西原老人. His four-character mnemonic on pulse theory, Sì yán jǔ yào 四言舉要 (alternately Cuī shì mài jué 崔氏脈訣 or Zǐxū mài jué 紫虛脈訣), is one of the most widely transmitted Sòng-era pulse texts; later Yuán-Míng-Qīng compilations cite or paraphrase it extensively. Survives via numerous derivative editions, including Pān Jí’s expansion KR3eb001 Yī dēng xù yàn, the bare-text KR3eb025 Mài jué, and KR3eb033 Mài xué lèi biān.