Source: Wikipedia

The Wuzhen Pian is a 1075 C.E. Taoist classic on Neidan-style internal alchemy. Its author Zhang Boduan (987-1082 C.E.) was a Song Dynasty scholar of the Three Teachings (Confucianism, Taoism, and Buddhism). The Wuzhen Pian is comprised of 81 poems and an appendix containing 12 alchemical ci ("lyrics") that correspond numerologically to the 12 months, and 5 verses related with the Wu Xing ("Five Phases.") The verses appear to be written as lyrics to be sung or chanted, and are full of paradoxes, metaphors, and aphorisms that lend themselves to multiple interpretations. Over the centuries, commentaries on it have been written by many Taoist and non-Taoist scholars. Contemporary translations into English further illustrate the difficulty of interpreting the esoteric symbolism.

The Wuzhen Pian is one of the major scriptures of Daoist Neidan ("Inner Alchemy"). The verses are widely accepted as an elaboration of the Zhouyi cantong qi, (Token for Joining the Three According to the Book of Changes), a first century apocryphal text associated with the I Ching (Book of Changes), but their philosophical basis is in the Tao Te Ching and the Huangdi Yinfujing. In Wuzhen pian, Zhang Boduan compares human life to a bubble floating on water or a spark from a flint, and concludes that the search for wealth and fame only results in bodily degeneration; human beings should search for the Golden Elixir to become celestial immortals. The human body already contains the essential components of the golden elixir: Jing, qi, and shen. Through alchemical refinement of bodily jing and qi, one can supposedly achieve integration with one's spiritual shen nature.

Author
Zhang Boduan, or Zhang Ziyang, was a native of Tiantai, in present-day Zhejiang. Biographical sources disagree over whether he was born in 983, 984, or 987. After passing the Imperial examination, he began a career as a civil servant, but was banished to the frontier in Lingnan, where he served as a military commissioner. Zhang was later transferred to Guilin and Chengdu, where in 1069, he allegedly experienced sudden realization from a Daoist Master who instructed him in Neidan internal alchemy. Zhang wrote the Wuzhen Pian, its appendices, and a few other texts, including the Jindan Sibai Zi ("Four hundred words on the Golden Elixer," translated into English by Davis and Chao in 1940). He was additionally an authority on Chan Buddhism.

Zhang Boduan died in 1082 C.E. during the reign of Emperor Shenzong of Song. Zhang was honorifically called Ziyang Zhenren, ranking him as a Daoist zhenren, one rank higher than a xian ("transcendent; immortal") in the celestial hierarchy.