Let me ask you a question, Lao Yang.

This ... seems to have never used the term "Taiyin Sun" in the Book of Changes ... It's a copper coin swaying on the meridians of Lao Yang, a traditional Chinese medicine in Laoyin. If three copper coins are two positive and one negative, it is shaoyang; Two opposites and one positive are shaoyin; Everything is positive, namely Lao Yang; It's all tails, it's old yin.

As the name implies, the Lao Yang of the old Yin means that Yin or Yang has reached the final stage. According to the principle that extremes meet, Lao Yang will become Yin (less Yin) and the old Yin will become Yang (less Yang). However, the change of less yin and less yang is different from the one directly obtained by pressing at first, which belongs to a change, that is, it represents a changing process. In divination methods, this change is of great significance. As for how important it is, it's a long story ~