The study of Emperor Qianlong of the Qing Dynasty is located in Xinuange, hall of mental cultivation, Forbidden City. Although it is only eight square meters, Emperor Qianlong has collected three works of ancient Mo Bao, namely "Sunny Post in Fast Snow" by Wang Xizhi, "Mid-Autumn Post" by Wang Xianzhi and "Yuan Bo Post" by Wang Xun. Wang Xizhi's "Eye-catching Post on the Fast Snow" is a letter written by the author to his relatives during the heavy snow in Chuqing, expressing the author's happy mood and greetings. It is named after the words "Eye of the Fast Snow" in the post. This post is free and easy with a pen, and the font is Shu Lang. This is a fine work in Wang Ti's running script. The book has twenty-eight characters, and every word is full of pearls, which is called "twenty-eight pearls" in history. It is the work of Wang Xizhi after the age of 40, and it is another masterpiece of running script after Preface to Lanting. This post was originally a family heirloom of Feng Yuanji who offered wine in imperial academy during the reign of Kangxi, and Feng Yuanji presented it to Emperor Kangxi. Emperor Qianlong cherished the "sunny post in the fast snow". In front of the post, I wrote eight small words "A westward journey, ancient and modern" and four big words "Thinking about its skills". During his more than 60 years in office, Gan Long wrote an inscription and postscript for this article for 73 times. Wang Xianzhi's Mid-Autumn Post is a paper book and a running script with three lines and 22 words. Wang Xianzhi is the seventh son of Wang Xizhi, and his calligraphy is influenced by his father. He further sublimated and refined Wang Tixing's brushwork. "Book End" said that the Mid-Autumn Festival post "is composed of one stroke and one word, with occasional disconnection, continuous pulse and staggered climate". The Mid-Autumn Festival post is an incomplete copy, and the original post also had the words "Not until December" before the Mid-Autumn Festival. Posts written on bamboo paper were not popular in the Eastern Jin Dynasty, but only appeared in the Northern Song Dynasty. As can be seen from the strokes, the brush used is a soft and unintentional pen, while the Jin Dynasty used a hard pen with a knot, which has poor water absorption, and it is often inflexible and not easy to lift, press and turn the pen, which often leads to thieves. The rich, mellow, coherent lines, smooth and elegant effect of such a post can't be written. This post is his work after the age of 50, and it is a handwritten note. Yuan Bo Post, this is a letter written by Wang Xun. The full text has six lines and 47 words, which is a typical running script of Jin Dynasty. Its content is narrative, and the name of the post comes from the first sentence "Yuan Bo". Wang Xun (349~400), nephew of Wang Xizhi. Dong Qichang commented: "Wang Xun is chic and ancient, and it is romantic in the Eastern Jin Dynasty." This post is a running script, vigorous with a pen, but scattered with charm. It was posted in Wu Xinyu, Xin 'an in the late Ming Dynasty, and later belonged to Wu Ting. 1746 was incorporated into the territory of the Qing Dynasty. Why did Emperor Qianlong attach so much importance to these three pieces of Mo Bao, but did not include the Preface to Lanting in Sanxi Hall? In fact, both Kangxi and Qianlong loved Wang Xizhi and Preface to Lanting. Kangxi sometimes read Preface to Lanting Collection several times a day. Qianlong had ten poems about Lanting in his life. In Lanting, Shaoxing, there stands a Lanting monument. The front of the monument is engraved with the Preface to Lanting Collection written by Emperor Kangxi, which is exquisite and elegant. On the back is the seven laws "Lanting is a thing" written by Emperor Qianlong. This monument is called "Lanting Imperial Monument", also known as the monument of grandparents and grandchildren. Two generations of emperors wrote a monument together, and their admiration for Lanting was beyond words, expressing the respect and admiration of the supreme ruler of Qing Dynasty for Wang Xizhi and Preface to Lanting. However, in Qianlong's eyes, the original preface to Lanting Collection has been brought to Zhaoling by Emperor Taizong, and only the copy of the Tang people exists. Although Feng Chengsu's Dragon Book and Preface to the Orchid Pavilion are the most exquisite handed down, they are "not as good as the original" after all, and Feng Chengsu himself is only a person who worships books in the ruling and opposition during the Zhenguan period, and is insignificant in the eyes of the emperor. Later, Emperor Qianlong decided to build eight pillars of Lanting in Yuanmingyuan, and collected the ink of Lanting posts of famous calligraphers in past dynasties. Feng Chengsu's "Dragon Book" and "Preface to Lanting" rank only in the third column, after Yu Shinan and Chu Suiliang in the Tang Dynasty. It can be seen that although he loves Lanting Preface, he does not attach great importance to it. On the contrary, he thinks that Quick Snow Clear Post, Mid-Autumn Post and Yuan Bo Post are all original works of Jin people, and "Jin people are as precious as a word", so they are regarded as treasures. Just as Qianlong wrote an inscription on Yuan Bo Post: "The original works in the Tang Dynasty are rare, and the people in the Jin Dynasty are so rare! The right army speed snow post and the big order mid-autumn post hidden in the palace are rare treasures. Today, the cocoon paper in Wang Xun is as beautiful as the family style! Several rewards are also helpful in the pool. " Don't you know that "Quick Snow Clear Post" and "Mid-Autumn Post" are not original works of Jin people? According to experts' appraisal, The Sunny Post on the Fast Snow was copied in the Tang Dynasty, while The Mid-Autumn Post was mostly thought to be copied by Mi Fei, a painter in the Song Dynasty, according to the research of contemporary calligraphy and painting appraisers. Sanxi Hall's three Mo Bao, only Wang Xun's Yuan Botie is authentic. Today, the sunny postal service of the fast snow is in the National Palace Museum in Taipei, the postal service of Mid-Autumn Festival and the postal service of Yuan Bo are in the National Palace Museum in Beijing.