The development of "Yi" thought of Yin and Yang thought is almost synchronous and inseparable with the development and change of "Yin and Yang thought". Fuxi era has entered the era of patriarchal clan society and male-dominated clan alliance. Ancestors have accumulated knowledge of survival and production for a long time, and their understanding of the law of the operation of heaven and earth and their insight into people and everything have gradually deepened. In the face of colorful nature, laws are summarized from natural social phenomena such as the sun and moon, day and night, men and women, men and women, cold and heat. Fuxi and the ancestors produced "Yang thinking" and "Yang thinking", sprouted and produced the idea of the unity of opposites of Yin and Yang, and summed up the "law of the unity of opposites of Yin and Yang", that is, the interrelated law of the unity of opposites of Yin and Yang. On the Taiji diagram of "one painting opens the sky", Yin and Yang are represented by simple and clear symbols, and all mysterious things are combined with sacred thoughts. Furthermore, from the practice of life, it is found that the yin and yang components of things are different, some have many yang components, some have external yang and internal yang, and some have internal yang and vulva, but they are all represented and classified by yin and yang symbols, so that all complex and contradictory things can be harmonious and unified. The thought of Yin and Yang produced by "positive thinking" embodies the major laws in a harmonious universe and society, concentrates the wisdom of Fuxi and our ancestors, deepens our understanding of everything composed of Yin and Yang, greatly promotes Fuxi culture and Fuxi civilization, and then leads and promotes Shennong culture, Huangdi culture and even Chinese culture and civilization. In the final analysis, "Yin-Yang Thought" was decided by patriarchal clan system and clan alliance society at that time, which is the mystery of "Yin-Yang Thought". Why did "Yin-Yang School Thought" later become "Yin-Yang School Thought"? When is the "changed" node? Through a lot of long-term analysis and research, it is found that the time of "change" is the end of Shang Dynasty, and the key figure is Xibo Hou Jichang, that is, Zhou Wenwang. At the end of Shang Dynasty, Xibo Hou Jichang was imprisoned. Due to the social and professional needs of destroying merchants at that time, he secretly concealed his great ambition of destroying merchants and prospering the Zhou Dynasty. This mentality and tactics belong to "Yin" rather than "Yang". This is the mystery of "Yin thinking". Therefore, Ji Chang struggled to change the social order and order, from the concept of "Yin-Yang Thought" dominated by Yang to that of Yin-Yang Thought, which was manifested in the arrangement of "playing eight diagrams", the deduction of sixty-four hexagrams, the implication of divinatory symbols and the strategy of keeping a low profile. From the social and historical point of view, the inversion of Yin and Yang reflects Ji Chang's status, status, living conditions, political needs and the present situation of concept development at that time. It was an epoch-making historical change, not a trivial detail, which directly affected the thinking mode and concept mode of later generations and affected all aspects of social life and ideological field. Scholars, including Confucius, are deeply influenced by the inversion of Yin and Yang in their casual or thoughtless analysis. Up to now, there are some logical confusions or confusions in social life, production and concepts. For example, the contradiction between the sun and the moon, the contradiction between men and women and the corresponding concept of yin and yang are actually traces left by the inversion of yin and yang; Quoting Xu Shen's words: "The sun and the moon change, just like Yin and Yang", which is also a concrete manifestation of the influence of the inversion of Yin and Yang. It should have been "the sun and the moon are easy, just like yang and yin."