30. YIXING
George A. KeyworthIn the conventional Sino-Japanese esoteric Buddhist traditions, Yixing
(673–727), born Zhang Sui in Henan province , is
counted alongside Śubhākarasiṃha (Shanwuwei , 637–735),
Vajrabodhi (Jin’gangzhi , 671–741), and Amoghavajra (Bukong
, 705–774) as the only preliminary Chinese exponent of the inno-
vative secret teachings that reached China during the reign of the august
emperor Xuanzong (685–762, r. 712–756). In the annals of Chinese
history, however, Yixing is much more famous as a scientist, mathema-
tician, and astronomer who built clocks, introduced Indian mathematics
(the Kutṭakạ method to solve equations), and produced the Kaiyuan-
era Dayan calendar between 721–727 (later condemned in
733 as a shoddy replica of the Indian Navagraha calendar; Needham
1959, 121, 202–203). Yixing gained access to Indian scientific knowledge
through his extensive comprehension of Sanskrit, which he learned as a
diligent disciple first of Śubhākarasiṃha and then of Vajrabodhi (Mat-
sunaga Yūkei 1969, 139; Lü Jianfu 1995, 226–227).
Biographical materials concur that Yixing was an exceptionally gifted
scholar. Despite rather humble beginnings, he studied Daoism and
read widely as a youth before taking tonsure at the age of twenty-one,
becoming a disciple of the eminent Chan master Puji (651–739)
on Mt. Song. He then went on to study monastic codes and
Tiantai meditation and doctrines before finally ending up in
Chang’an by 716. There he encountered Śubhākarasim ̣ha, and
the two men jointly translated the Mahāvairocana sūtra (Dari jing
, T. 848), which sets forth the womb mandala (garbhadhātu,
taizangjie ). Yixing’s biographies suggest that he trained with
Śubhākarasiṃha for eight years before Vajrabodhi’s arrival in Luoyang
, when Yixing became familiar with the teachings of the diamond
mandala (vajradhātu, jin’gangjie ) expressed in the Vajraśekhara
sūtra (Jin’gangding jing , T. 866), though the concept is much
more fully developed in the translations supervised by Amoghavajra
(Song gaoseng zhuan 5, T. 2061, 50.732c7–733c24). The
degree to which Yixing’s views of esoteric practices were influenced