Yuanhai Ziping
Yuanhai Ziping () is the first comprehensive and systematic book on the theory of Four Pillars of Destiny. The book was compiled by Xu Dasheng (徐大升, aka Xu Ziping , hence the book's name) of the Song Dynasty of China. It is a recording of various Zi Ping's fortune-telling methods. The method involves manipulation of the Four Pillars, each consisting of the two Chinese characters for the date and time of a person's birth (alternative name "eight characters" 八字 "Ba Zi"). The names of the book's chapters are: