Because eccentricity cannot be used alone (it is a failure to use it alone), it can only be used in combination with the center, while the pen used by the center is basically only written in two ways: eight points and flying white. Cai School is the founder of calligraphy, the master of seal script and official script, and the main creator of the eight-part essay of official script. In Nine Trends, he emphatically summarized the writing experience of stereotyped writing style, clearly pointed out that the front part of writing is the rule of "horizontal ruler and vertical restraint", and specifically explained the writing methods such as "the heart of the pen is always constant" and "turning the pen to review", and explained the writing methods such as illness and astringency. In the official script style, Cheng Gongxiang also clearly pointed out that the calligraphy style of mature official script style is "horizontal and vertical, left and right". "Samadhi Calligraphy" also clearly stated that "the painting is divided into seal script, and the front is wrong." This swimming stroke with both middle oblique front and middle oblique front is based on the middle oblique front, combining the methods of paving front, diving front, dragging front, keeping front, 9 front, frustrating front, releasing front and converging front. The methods of writing strokes are as follows: horizontal drawing is the scale of drawing the pen, so that the pen center moves frequently in the painting, and the pen tube is twisted, so that the pen tip naturally swings sideways (such as the rotation of bicycle wheels), and the strokes are round and flat, showing a square and flat situation; Vertical painting is to draw the strokes straight down, spread out the front, and write them like a flute board to show the characteristics of square flat body, row upon row, precision and fierceness, which is "dangerous and terrible". Unfortunately, the decorative writing of official script has been lost because of "ancient and modern resistance".
As for Cai Pai's brushwork of flying white, it is the inspiration from watching craftsmen paint walls. Although the so-called "graceful people fly white" is difficult to test, the strokes are inevitably "rough and dry", both flying white and sketching.