Why can Ou Yangxun's calligraphy in the Tang Dynasty be "choosing what he likes and getting what he likes"?

There are several reasons why Ou Yangxun's calligraphy can "not choose the pen or the paper". First, the calligraphy skills are relatively high. People with a high level of calligraphy can use calligraphy skills instead of paper and pen to write well. For example, calligraphy creation pays attention to the use of the nib, which is the front end of the brush and a stroke near the front end. He Jiang of A Qing Dynasty said, "If you are good at dancing with a pen, you will know how to dance with a pole. If you are good at using a gun, your strength lies in the tip of the gun. " You can't write when the steel ball at the tip of a ballpoint pen is broken, just like a brush. Once the nib is broken, it is difficult to write well. Therefore, calligraphy creation often pays attention to "three-point pen", that is to say, the pen used in writing should not exceed three-sixths of that used in writing, and it is possible to use "big strokes to write small characters" instead of "small strokes to write big characters", so as not to destroy the flexibility of the pen. However, the great calligrapher is an exception, because he can violate the principle and write with a pen.