It is said that calligraphy has one to nine grades. What's the difference between level one and level nine? What is the concept of each level?

I am not a professional, and my answer is not in place. Please forgive me. The following points are for discussion. First, from the basis of calligraphy: one to nine represents the basic skills of writing; Second, from the book: one to nine represents the unity of spirit and spirit; Thirdly, from the perspective of cultural inheritance, the first level means that we know something about the ancient culture of China. With the deepening of calligraphers' interest and higher level, our understanding of ancient China culture will be more rational and comprehensive. Fourth, from the aesthetic point of view: one to nine represents the qualitative aesthetic feeling of art; Five, from the philosophy of life: one to nine represents the level of calligraphy. The so-called "to be alive and create a state of mind" is the philosophical version that most people pursue? )