Using the pen in the center means: always make the center of the pen move in the middle of the dot painting. Center strokes are the only rule of traditional calligraphy. But it is absolutely impossible for the center of the pen to always walk in the middle of the stipple, so if the center of the pen is biased to one side, it is called a side edge. The middle and side are a pair of concepts. Hiding the front means: "If you want to look left or right, you should go down first if you want to go up." That is, at the beginning of the stroke, stroke in the opposite direction and hide the tip of the pen in the stroke. The exposed edge is just the opposite. It exposes the edge of the pen, reflecting the continuous trend of looking, looking, and responding. The theory of "shun" and "ni" means: "resistance" means that the penholder tilts in the opposite direction of the stroke of the pen. It is called "resistance" when sharpening and practicing. "Shunni" means that the direction of the penholder Qingdao is consistent with the direction of the stroke of the pen. Zhefeng means to adjust the direction of the stroke by moving the pen, causing the direction of the stroke to change. Traditionally, it is generally called folding pen, which is different from turning pen. When turning the pen, there should be a twisting action, that is, twisting the tube. Sharp edges and pointed edges are stroke shapes, which can be seen by observing the handwriting. I hope the error will be corrected.