In fact, in ancient China, for a long time, ancient people's contracts were signed with "paintings" because the literacy rate of ancient people in China was very low. Then you may have a question in your heart: isn't it easy to draw a circle on paper? Why did the ancients use this method as a signature? Aren't they afraid of being impersonated?
This will start with the history of signing and signing. According to the records of ancient historical materials, the inscription of this painting should have originated in the Tang Dynasty. At that time, if you left your personal notes on documents, calligraphy and paintings or contracts, it was called "pledge", which was equivalent to "signature" and "signature" now.
At that time, except for the memorial presented to the emperor, cursive script was forbidden, and all kinds of fancy personalized cursive script were generally used in other contracts and documents. These signatures were collectively called "flower script".
In the Song Dynasty, when writing official documents, officials in the Song Dynasty generally only wrote their names at the end of the official documents, so it was also called "betting words". For example, Wang Anshi, the famous prime minister of the Song Dynasty, wrote the word "stone" in his signature, leaving only one, one of which was taken away, and the word "mouth" was directly omitted below. Later, an official said that his signature looked like a "reverse", so he added a circle in the middle instead of the word "mouth".
Then the problem is coming. Most people were illiterate at that time. What should they do if they need to sign? So many people had a brainwave and asked the people to imitate Wang Anshi directly and draw circles instead. This is the origin of the so-called "painting". In fact, when officials draw vows, they usually need ordinary people to press their handprints as auxiliary evidence, so the vows themselves may be just a symbolic meaning.
On the other hand, because many ordinary people are new to writing brush, it is very difficult to draw a complete circle, so the patterns they draw have certain particularity. For example, Ah Q wants to draw a circle, but it turns out to be a melon seed shape. Therefore, in fact, painting itself also has special significance in identifying ordinary people.