Gangua is one of the sixty-four hexagrams in the Book of Changes, which means humility, modesty and concession. In the dry divination, the first thing that comes to mind is Shaoyin, which represents the initial stage of the development of things; The second is Lao Yang, which represents a turning point in the development stage; Three evils are shaoyin, which represents the internal essence of development; Fourth, shaoyang, representing external performance and action; Five evils are shaoyang, which represents the peak of the development of things; The hexagon is less cloudy, representing the retreat stage.