Wúxué Zǔyuán 無學祖元 / 子元祖元 (Jp. Mugaku Sogen, 1226–1286) — Late-Sòng Chinese Línjì-school Chán master who emigrated to Japan in 1279 and became the founder of Engaku-ji 圓覺寺 in Kamakura — one of the Five-Mountain (五山) temples of the Kamakura system. Style-name Ziyuan 子元, sobriquet Wuxue 無學 (“Beyond Learning”). Posthumous imperial title Bukkō Zenji 佛光禪師 (“Buddha-Light Zen Master”); later elevated by Emperor Jōji 貞治帝 (Go-Murakami) to Bukkō Enman Jōshō Kokushi 佛光圓滿常照國師 (“Buddha-Light Universally-Complete Ever-Illuminating National Master”).
Born Bǎoqìng 2 (1226) in Mìngzhōu 明州 (modern Níngbō, Zhèjiāng) — per Bukkō Zenji tōmei 佛光禪師塔銘 (his stūpa-inscription preserved in fasc. 9 of his yulu). Received Línjì-school transmission from Wúzhǔn Shīfàn 無準師範 (1178–1249) at Jìngshānsì 徑山寺 — like 圓爾 Enni Ben’en before him. Travelled and taught at Tiānzhēnsì 天眞寺, Tāizhōu Zhēnrúsì 台州真如寺, and other major Sòng monasteries.
In Kōan 2 (1279), with the Mongol invasions threatening south China, he travelled to Japan at the invitation of the regent Hōjō Tokimune 北條時宗. Welcomed at Kenchō-ji 建長寺 in Kamakura; in Kōan 5 (1282) Tokimune founded Engaku-ji 圓覺寺 to commemorate the war-dead of the Mongol invasions, with Wúxué as founding abbot. Died at Engaku-ji on the 3rd day of the 9th month, Kōan 9 (1286), age 61 (per his stūpa-inscription).
His Recorded Sayings — Bukkō Kokushi goroku 佛光國師語錄 (KR6t0255, T80n2549) — ten fascicles, compiled by Yīzhēn 一真 and others; redacted with an extensive preface that situates him alongside Confucius, Mencius, and the Buddha at Vulture-Peak as a “universal” sage. The work is one of the most elaborate Japanese-period yulu of the Five-Mountain era. His Japanese disciple Kōhō Kennichi 高峰顯日 was the master of Musō Soseki.
Source: Bukkō Zenji tōmei; Bukkō Kokushi goroku preface; standard Japanese-Zen biographical sources; Dumoulin, Zen Buddhism, vol. 2: Japan, pp. 30, 36; Collcutt, Martin, Five Mountains (1981).