Why can't the words on the plaque be the same as the name of the Qing emperor?

That's because we have to avoid the emperor's taboo, which is taboo.

Taboo is a unique phenomenon in China feudal society, which began in Zhou Dynasty, became in Qin Dynasty, flourished in Tang and Song Dynasties, and became closer in Qing Dynasty. At that time, people could not call the emperor or his elders by their first names, otherwise they would be in danger of going to jail or even losing their heads because of taboos. The common taboo method is to change the words to be taboo into other words with the same or similar meaning. As a result, there have been many strange phenomena in the history of China in which names of people, places or things have been changed.

There are four types of taboo objects:

One is the emperor, avoiding the names of contemporary emperors and emperors of past dynasties. For example, during the Liu Xiu period, the scholar was changed to Cai Mao; Ganlong once wrote a letter to the door, saying that Five Blessingg was not allowed in the couplet, in order to avoid the name of the emperor shunzhi Fu Lin. Sometimes they even avoid using the queen's name, such as Lv Hou's name, and courtiers have to change their names to pheasants when they meet pheasants.

The second is to avoid the names of officers, that is, subordinates should avoid the names of officers themselves, their fathers and grandfathers. Even some arrogant officials strictly ordered their men and people to avoid their names. There is a story in Lu You's Notes on the Old Learning Temple: a state official named Tian Deng, his subordinates and people in the state are not allowed to call his name or write his name. On the fifteenth day of the first month, turn on the lights for three days as usual. The little official who wrote the notice did not dare to write the word lamp, but changed it to "the state government set fire to it for three days according to law." This led to the joke that "only state officials are allowed to set fires, and people are not allowed to light lamps".

Third, avoiding sages mainly refers to avoiding the name of sages Confucius and Mencius. Some dynasties also avoided using the name of Huangdi, the ancestor of the Chinese nation, and some even avoided using the name of Duke Zhou or even Laozi.

The fourth is to avoid elders, that is, to avoid the names of parents and grandparents. When dealing with people, it is very impolite to avoid the taboos of the other elders. Li He, a poet in the Tang Dynasty, had a father named Jin, and "Jin" and "Jin" are homonyms, so Li He could not be a scholar all his life. In A Dream of Red Mansions, Lin Daiyu's mother's name is called, so whenever she meets Min, Lin Daiyu pronounces it as "trick" or "secret".

The ancients often needed to avoid taboo, and they summarized various methods of taboo:

Change fonts. Some use words with the same (similar) meaning instead of words that need to be avoided. For example, when Emperor Wu of the Han Dynasty became famous, the famous debater Kuaiche changed his name to Tong. When Tang Gaozong ruled by name, everyone in the world replaced the rule of words with the rule of words. Sometimes it can be avoided by adding and subtracting strokes. For example, Qiu's ancestor was originally named Qiu, but Confucius was named Qiu, so an ear was added to avoid it. Since the Song Dynasty, people have avoided the word "autumn". When writing, they often omit a stroke, and some people write □ or leave blank.

Change pronunciation. For example, Qin Shihuang is famous for ruling the world, so the first month is about to be read as life. Some people read a word instead of a word, and read a word that should be avoided and change it to a word.