Originally named Zhang Sui (), Yixing (), was born in Changle, Weizhou (modern Nanle in
Hebei) though other sources suggest his birthplace was Julu, present-day Pingxiang, Hebei. A great-grandson of the Tang dynasty statesman Zhang Gongjin (; 584–632), Yixing came from a distinguished family, possibly influencing his later connection to the Tang court. His early intelligence was recognized in the
Jiu Tang shu, which records his precocious mastery of classical texts, particularly in
astronomy,
calendrical science, and traditional
Chinese philosophy. After the deaths of his parents at age 21, Yixing renounced secular life and was ordained as a
Buddhist monk. He trained under several masters, including Hongjing and Facheng, and later under Puji at Mount Song, receiving transmission within the Northern Chan lineage. His deep cultivation of "single-practice samādhi" () led to his monastic name, and there is evidence suggesting he was also a disciple of Shenxiu. Throughout his early career, Yixing displayed exceptional devotion to the study of the
Vinaya, and he composed a now-lost treatise on Vinaya essentials. During the early eighth century, Yixing avoided political entanglement with powerful figures such as Wu Sansi, choosing instead a life of itinerancy, seeking Buddhist instruction throughout the southern regions. He studied the "Indian Vinaya" under Wuzhen at Mount Dangyang and received additional teachings from the monk Daoyi. In 717,
Emperor Xuanzong personally summoned Yixing to the capital, where he became an esteemed religious advisor, frequently consulted on matters of governance and the welfare of the people. Yixing spent his final years primarily in
Chang'an and
Luoyang, focusing on religious activities. In 727, after a period of illness during which extensive
merit-making ceremonies were performed for his recovery, Yixing died while traveling with the emperor. Xuanzong composed the inscription for his memorial
stele, and posthumously conferred upon him the title Meditation Master Dahui (). Yixing’s most significant contributions during his later life centered around his involvement in the translation and interpretation of
Esoteric Buddhist texts. He collaborated with the Indian master
Śubhakarasiṃha in translating the
Mahāvairocana-sūtra, working primarily as an editor and recorder rather than as a direct translator, suggesting limited proficiency in
Sanskrit. The surviving Chinese translation condenses the much larger Sanskrit original. Yixing also compiled an influential commentary on the
Mahāvairocana-sūtra, preserving Śubhakarasiṃha’s oral teachings while incorporating his own notes and references to Chinese Buddhist sources. Two versions of this commentary survive, the
Dari jing shu () and the
Dari jing yishi (). The work reflects a synthesis of Esoteric Buddhist thought with elements of
Huayan philosophy and cites seminal texts such as
Nāgārjuna’s
Madhyamaka-śāstra and the
Da zhidu lun. In addition to his work with Śubhakarasiṃha, Yixing is also reported to have studied under
Vajrabodhi, from whom he received the
Vajraśekhara abhiṣeka initiation and whom he assisted in translation efforts. His literary contributions extend beyond Esoteric Buddhism; the
Jiu Tang shu lists a lost work titled
Shishi xilu (), which appears to have covered a wide range of monastic regulations and practices. Yixing's legacy, while celebrated for his astronomical and calendrical reforms in secular histories, is equally significant in the Buddhist tradition for his pioneering role in the early transmission of
Esoteric Buddhism to China.
Legends Yixing’s prominence gave rise to many legendary narratives about him. Japanese sources recount that when Yixing’s mother was pregnant, a halo of white light appeared on her forehead, later transferring to the newborn Yixing. Stories portraying him as an extraordinary figure also circulated in Tang dynasty literature, indicating his influence beyond Buddhist circles. Notably, texts like the
Kaitian chuanxin ji,
Minghuang zalu buyi, and
Youyang zazu record anecdotes of Yixing appearing as a spirit and bearing the Daoist title "Heavenly Master." Moreover, the
Jiu Tang shu describes Yixing’s encounter with a
Daoist named Yin Chong, from whom he borrowed the
Taixuan jing. Demonstrating rapid mastery of its profound teachings, Yixing impressed Yin Chong by producing new scholarly works. Such tales, while celebrating Yixing’s intellect, are likely hagiographical embellishments intended to bolster his reputation. Another account details Yixing’s search for instruction in the
Yijing’s number theory, eventually leading him to
Guoqing Temple on Mount Tiantai. According to legend, he was foretold by a monk within the temple and miraculously admitted when the waters outside reversed their flow, symbolizing his destined arrival. Although framed within Buddhist texts like the
Song Gaoseng zhuan, this story is more connected to mathematical traditions than Buddhist practice. In the late Tang, as foreign astrology gained prominence and astral magic merged into both Buddhism and Daoism, Yixing’s image evolved further. He became associated with esoteric rites involving stellar deities, such as summoning the gods of the 28 lunar stations, as recorded in the
Qiyao xingchen bie xingfa. These accounts, blending elements of Mantrayāna and astrology, reflect a mythologized view of Yixing shaped by the cultural and religious currents of the time. ==Astronomical work==