In the Tang Dynasty, "Sui" was a special word for the royal family, and only the emperor himself could use and write it. Many things in the Tang dynasty have strict requirements, and ordinary people can't use them. For example, the emperor's special words are one of them. Another example is the emperor's dragon chair. Even if others don't want to touch it, they are not allowed to think about it. This is the supreme power of imperial power. This is a way to deify and hold high the imperial power. If someone violates it, it is a capital crime. Even if his grandson violates the rules, the punishment is quite severe.
Li Zhi, the youngest son of Emperor Taizong, has two brothers. Once, Li Shimin and his grandson played with Li Zhi. Li Zhi was a little boy and played all day. One day, Li Zhizheng picked up a pen and wrote on a piece of white paper, which covered the whole paper. Seeing Li Zhi's love for graffiti, Li Shimin was curious. What he drew on the paper aroused Li Shimin's curiosity. Li Shimin took the paper and smiled at Li Zhi's graffiti. He wants to know what a happy day it will be for a free and carefree child.
However, Li Shimin was surprised. It turned out that Li Zhi scribbled on the painting and calligraphy, and the word "Yi" was clearly visible. Then he said to the maid-in-waiting, "Burn this paper at once and don't tell anyone." Li Shimin thought it was an act of god. Of course, Li Shimin was not afraid that Li Zhi would take his throne. At this time, Li Zhi is still an ignorant child and will not pose any threat to himself. He did it to protect him. After all, he has two brothers. Sure enough, Li Zhi finally became emperor, which is probably an act of god.