Laozi is the most important contributor to the development of the Book of Changes.

Laozi not only wrote the "Four Wings" of the Book of Changes, but also wrote the Book of Changes, that is, hexagrams and poems. When Confucius visited Laozi for the last time, Laozi gave him Sixty-four Gua and Three Hundred and Eighty-four Gua, which he had hidden in Zhoushou barn for decades, as well as Shangxia Gua and Daxiang Gua, which annotated and extended the meaning of hexagrams. Lao Tzu kept a low profile and told Confucius that it was a divination book of sixty-four hexagrams explained by the late king, but it was more suitable for Taoism than Lian and Gui Zang Yi. Laozi is already familiar with Confucius' hobby "the trace of the former king"

To sum up, the system of the Book of Changes is as follows: the eight diagrams were created by Fuxi, and the king of Wen interpreted them as sixty-four hexagrams. The initial structure of the book of changes was formed by drawing symbols and hexagrams; Laozi wrote Zhuan Xu Biography (Up and Down) and Xiang Biography (Size) in the classic Guaci, Yi Ci and Ten Wings. Classical Chinese, inheritance (up and down), preface and divination, narration and miscellaneous divination in Ten Wings of Confucius. A book of changes, Lao Zi and Confucius each wrote six major parts.