Yixing Chanshi （683-727）. Chinese monk of the Tang dynasty， acknowledged as one of the eight patriarchs of the doctrine 傅授八祖 in Shingon lineages. He joined the priesthood after the sudden death of his parents in 704， having previously distinguished himself in Taoist circles. He studied Chan 禅 at Mount Son 嵩山 with the seventh patriarch of the northern school， Puji 普寂 （631-739）， and studied Vinaya with Huizhen 惠真 （673-751）， a disciple of Hongying 弘景. In addition， while on Mount Tendai 天台山 he studied mathematics and astronomy， complementing his widely-recognised expertise in Taoist divination and calendrical science. In 716， he became the disciple of S/ubha^karasim!h!a 善无畏， subsequently receiving a summons to the court of emperor Xuanzong 玄宗. He was also initiated into various esoteric practices by Vajrabodhi 金刚智 shortly after their first meeting in 720. His most accomplished work， a huge commentary 大日经疏 （T 1796） on the Vairocana^bhisam!bodhi 大日经， was completed in 725 CE. Yixing is also popularly remembered as the inventor of the armillary-driven clock.