Xú Zǐpíng 徐子平
Personal name Jūyì 居易; the zì form Zǐpíng 子平 became universal. The ultimate authority of late-imperial Chinese bāzì (eight-character) fate-divination — to such an extent that the technique is universally referred to as Zǐpíngshù 子平術 (Zǐpíng’s technique) in late-imperial Chinese culture.
Per the late-Míng Liú Yù 劉玉’s Yǐnnüè biān 已瘧編 (cited by the Sìkù 提要 of KR3g0037): “the jiānghú (rivers-and-lakes) [popular] discussers of fate have Zǐpíng and have Wǔxīng [five-planet]; tradition holds that there was Xú Zǐpíng of the Sòng who was refined in star-learning, [whose name was] taken-up by later technique-practitioners — therefore [the technique is] called Zǐpíng”. The same source records: “[Xú] Zǐpíng’s name was Jūyì 居易, a Five-Dynasties man; with [the legendary] Mǎyī Dàozhě 麻衣道者, [the recluse] Chén Túnán [陳摶], and [the immortal] Lǚ Dòngbīn 呂洞賓 he hid together at Huáshān 華山 — indeed [he was an] extraordinary person”.
The Sìkù 提要 records the alternative tradition: “The present-day discussers of Zǐpíng [refer to] Xú Yánshēng 徐彥昇 of the late Sòng, not [the original] Zǐpíng” — suggesting that the late-imperial Zǐpíngshù descends from a Southern-Sòng intermediary (Xú Yánshēng) rather than directly from the legendary Five-Dynasties Xú Jūyì.
The Sìkù-preserved Luòlùzǐ sānmìng xiāoxī fù zhù 珞琭子三命消息賦註 (KR3g0037) — in 2 juàn, attributed to Xú Zǐpíng — is the foundational document of the late-imperial bāzì fate-divination tradition. Through this work, the bāzì methodology (analyzing personal fate from the year-month-day-hour eight characters of the heavenly-trunk / earthly-branch combinations at birth) became the dominant late-imperial Chinese fate-divinatory practice, replacing the older Tang Lǐ Xūzhōng three-character (year-month-day) methodology.