Why is Lanting Preface called the top national treasure?

Liu Zhengcheng wrote in Introduction to Calligraphy Art: "The artistic value of Preface to Lanting is not only reflected in its exquisite pen and ink skills and integrity of composition, but also in the profundity of cultural and emotional expression integrated with the author. Preface to Lanting possesses all the aesthetic factors of calligraphy from calligrapher, calligraphy, content and form. Under the ideological and cultural background of metaphysics in Wei and Jin Dynasties, scholars' comments, scholars' appreciation of algae, and the collapse of Confucian classics in Han Dynasty, Preface to Lanting, as the "first running book in the world", completely got rid of the sub-artistic position of calligraphy attached to words and serving decoration for thousands of years and became the best classic to express personality, poetic feelings and humanistic value choices. Wang Xizhi, who was honored as a "book saint" by later generations, is shocking with his lofty personality charm, self-esteem and broad-minded feelings of transcending life and death. "

Preface to Lanting is the pinnacle of China's writing style, which belongs to Wang Xizhi's works in the mature period of calligraphy. Its writing, style and structure have reached a high level. Later calligraphers took the Preface to the Orchid Pavilion as the object of copying and imitating, such as Chu Suiliang in the Tang Dynasty, Yu Shinan and even Ou Yangxun, all of which had their own meanings, souls and personalities. Even Wang Xizhi himself later rewrote it many times, but it never reached the level of the first time. It can be said that this is an unprecedented work. In addition, the original was buried with Emperor Taizong and Li Shimin. Later generations only have rubbings, but the quality is not high. The nuances of those strokes can't be handed down at all.