What is the theory of yin and yang?

What is the theory of yin and yang?

The concept of yin and yang originated in the Xia Dynasty, based on the book "Lianshan" written in the Xia Dynasty ("Lianshan", "Gui Zang", and "Zhou Yi" are the Three Changes). Yin and Yang lines have appeared in the book "Lianshan". The theory of yin and yang divides all things in the universe into yin and yang, and believes that the formation, development and movement of all things depend on the movement and transformation of the two qi of yin and yang. The concept of yin and yang comes from the alternation of night and day and the back of sunlight. The side facing the sun is called yang, and the side facing the yin is called yin. Continue to extend and further explain all the phenomena in nature and society. The concept of yin and yang became the theory of yin and yang after the Zhou Dynasty, especially in the Book of Changes , which comprehensively summarized yin and yang and became a systematic and complete theory of yin and yang. All bright, outside, above, hot, moving, fast, male, strong, singular are masculine; all dark, inside, below, cold, quiet, slow, female The weak, the weak, and the even number are all feminine. The two are interdependent and united in opposition. The ancients' discourse on the dependence, opposition and transformation of yin and yang possessed the world outlook and epistemology of modern materialist dialectics.