Wuxing dayi 五行大義 "The Great Meaning of the Five Agents" is a philosophical treatise written by the Sui-period 隋 (581-618) master Xiao Ji 蕭吉 (d. 614), courtesy name Wenxiu 文休. He hailed from Nanlanling 南蘭陵 (modern Wujin 武進, Jiangsu) and also compiled the Diwang yangsheng yaofang 帝王養生要方, a book about medicine.
In the bibliographic treatises in the official dynastic histories Jiutangshu 舊唐書, Xintangshu 新唐書 and Songshi 宋史, this book is listed among the treatises on the Five Agents (wuxing 五行), with a length of 5 juan. It is divided into 24 chapters and 40 sub-chapters. The first fascicle is concerned with definitions and methodical discussions, while the rest of the book disputes the theory of the Five Agents and their influence on all aspects of the universe, from the human character and virtues to the musical pitch pipes, the eight winds, the organs in the human body, astronomy, geography, medicine, zoology, and many more aspects of life and religion.
The author is of the opinion that the Five Agents were the ground of all creations and also of human relationships. The five measures (wudu 五度) of Heaven were to be seen in the movements of the celestial bodies, the "five elements" (wucai 五材) of the Earth in the richness of is sources, and the five virtues (wude 五德) of man in the expressions of virtues. In order to clarify their meaning for human life, it was important to carry out prognostications with the help of numerology and other divinatory methods.
The text was finished in 617 and is preserved in a Japanese print from 1699. It makes use of numerous ancient sources on the Five Agents.