Yao Nai, a giant of the Tongcheng School in the Qing Dynasty, said: "Those who derive from the beauty of yang and strength will have their writing like a thunderbolt, like electricity, like a windy valley, like a high mountain and steep cliff, like a jue A great river is like a galloping horse; ...those who obtain the beauty of yin and softness will write like the rising sun, like the clear wind, like the clouds, like the clouds, like the smoke, like the winding streams of the secluded forest, like the fall, like the ripples, like The brilliance of pearls and jade is like the cry of swans entering the vast sky;... (Yao Nai's "Fu Lu Jie Fei Shu")