Who is "Cai" in "? When it comes to calligraphy in Song Dynasty, there are four great calligraphers who call it "Su Huang Camouflage". The four of them are considered as typical representatives of calligraphy style in Song Dynasty. Among the "Song Sijia", the top three are Su Shi (Dongpo), Huang Tingjian (Fu Weng) and Mi Fei (Xiangyang Manshi). Judging from the style of calligraphy, Su Wu is full of ups and downs and innocence; Huang tingjian rises vertically and horizontally, hiding and pulling; Miffy is handsome, bold, calm and happy. They were all good at learning from the ancients, full of innovative spirit and unique book style, and were highly respected by people at that time. They are listed in four schools, and there is no objection to this. Who "Cai" refers to has always been controversial, but it ranks at the bottom of the four schools. It is generally believed that Cai refers to Cai Xiang (). His calligraphy is based on the Jin and Tang Dynasties, paying attention to the ancient meaning and statutes. Its block letters are dignified and steady, its running script is pure and beautiful, and its cursive script adopts the method of flying white, which is called "scattered grass", which is self-contained and very beautiful. Hong Renzong loved books very much, and once "inscribed the inscription of Yuan Jiu's" Longxi King "to make it a book of life" and "made the book a monument to his father's warmth" (Biography of Cai Xiang of the Song Dynasty). Cai Xiang's calligraphy art was also valued by scholars at that time. Huang Tingjian once said: Both Cai and Ouyang Xiu (Collected Works of the Valley) said: "Mo Jun lives alone in the world, but refuses to lead the alliance with humility." (Ouyang Wenzhong's public collection) Su Wu pointed out in Dongpo's inscription: "Cai is the first in this dynasty with his high talent, profound knowledge and endless transformation." Since it is "the first" and since its calligraphy has always been the "main league", it should be well-deserved to be listed as the four major schools. However, since the Ming and Qing Dynasties, there has been another saying. Judging from the arrangement order of the four schools and the characteristics of the times, "Cai" originally referred to Cai Jing, and it was only after later generations hated him that it was replaced by Cai Xiang. The appraisers of calligraphy and painting in Ming Dynasty said in Fang: "The calligraphers in Song Dynasty were Su, Huang, Mi, Cai and Wei Jingyi. Later generations hated him as a man, so they went to court and entered your ears. Before Su and Huang, they should not be listed later. It is undoubtedly Beijing. The Beijing School's brushwork is charming, and it is not comparable to Mo Jun. " Sun Du of Ming Dynasty also said; "Cai Jing is the most famous Cai in the Song Dynasty. Now it is easy to be indifferent to you, so the younger generation is upside down ..." ("Postscript of Painting and Calligraphy") An Shifeng's "Moline Pleasure" further obscures Cai Jing's topic, saying; Cai Bian is better than Cai Jing, and Cai Jing is better than Cai Xiang. "Fortunately, there is a ban and no Cai." In Qing Dynasty, Hang Shijun also took "Su Huangmi, Cai Fei and Cai Xiang" as an example of "human error". It can be seen that "Cai Jing Theory" had a great influence in the Ming and Qing Dynasties. In all fairness, the proposal of "Cai Jing Theory" does have some truth. Cai Jing's calligraphy art has the characteristics of verve, boldness and calmness. Compared with Cai Xiang, which has preserved more "ancient laws", Cai Jing's calligraphy seems to be more innovative and can better reflect the aesthetic taste of calligraphy in the Song Dynasty. Therefore, it enjoyed a high reputation at that time, and many people studied its books in the government and the public. Yuan Tao chiayi's "Book History Society" once quoted critics at that time as saying; "Its strict and informal, is nothing more than rules. Books are like swords, and they are discussed in the temple; Running script is like a noble son, full of enthusiasm and brilliance; The big characters are the best in the world, and there are few horses. " It can reflect Cai Jing's position in calligraphy art at that time. Secondly, Cai Xiang's calligraphy was praised as "the first in the North Song Dynasty" in the early years, but since the formation of the new book style in the Middle Northern Song Dynasty, people have gradually criticized Cai Xiang's calligraphy. Su Dongpo mentioned many times in Dongpo's inscription that "those who wrote Mo Jun in recent years have quite different opinions", and that "Mo Jun is the best in the world, and the critics are not". Although Su Shi always insisted that Cai Xiang should be the first, at least in the middle and late Northern Song Dynasty, people's evaluation of Cai Xiang was not so consistent. Thirdly, from the arrangement order, the arrangement of Su, Huang and Mi has obvious generational order. Cai Xiang is a Renzong, ranking first among Zhezong and Huizong, second only to Mi Fei. There are some doubts. In this regard, people who insist on "Cai Xiang's theory" retort that although there is no "Song Sijia" theory in Song literature so far, Cun Wang, a adherent of the Southern Song Dynasty and Yuan Dynasty, has clearly put forward the "four schools" theory. In the ink of Postscript Cai Xiang Tao and Shi Yanming, he said that Cai Xiang's calligraphy was "sparse and self-contained, and there were four calligraphy schools at that time. A sneak peek, Dongpo muddy cycle looks the strongest, Fucheng Weng is thin and hard, Xiangyang changes vertically and horizontally, but it is better to put pen to paper. If you are indifferent, look at those people with rope rulers, and you will be selfless. Thus, it is pointed out that there were not only four schools at that time, but also these four schools were obviously Su, Huang, Mi and Cai. In addition, in the history of calligraphy, Cai Xiang's achievements in calligraphy are obvious to all, and his calligraphy style is unique, and he has also contributed to rejecting calligraphy and revitalizing the style of calligraphy. So overall, his achievements are obviously more than Cai Jing's. Regarding the arrangement order, Zhang Boju once pointed out in the article "The Book of Song Sijia" that "the order should be Cai, Su, Mi and Huang, and the general pronunciation should be Su, Huang, Mi and Cai, which means that it is a habit to equate Yin and Yang. "It shows that this arrangement is only formed by the fluency of pronunciation, and has nothing to do with the seniority of the four masters. It seems that "Cai Jing Theory" is not nonsense, and "Cai Xiang Theory" is well-founded. Because Cai Jing is one of the "Six Thieves", it is really difficult for people to accept him emotionally, so people tend to Cai Xiang. But it seems that the final conclusion of this problem should be confirmed by the literature of Song Dynasty.