The protagonist tells Ying Zheng's fortune.

During the Qin Shihuang period, someone worked out his five elements. Finally, according to the inference results, it is best for Qin Shihuang to wear a black dragon robe. It is estimated that the scene at that time was that a group of old men with white beards and dragon robes were fooling around with Ying Zheng, and perhaps they could come up with the rhetoric of wearing black dragon robes for generations, but Qin Shihuang not only believed it, but also believed it. So at that time, Qin Shihuang not only wore black dragon robes himself, but also let all the servants around him wear black skirts.

First, the five elements told the mysterious fortune teller of Qin Shihuang that it should be the yin and yang family. The calculated result is that Qin Shihuang belongs to water, so he should advocate black. Now it seems that this result may be unreliable, but at that time, people were convinced of the five elements and Zhouyi, and sometimes the results inferred from Zhouyi and the five elements were indeed consistent with the facts.

Second, the Han Dynasty inherited the old tradition. Because of this, even if the black dragon robe did not bless the Qin Dynasty, thousands of generations were still willing to believe in the five elements. So in the Han Dynasty, officials suggested that Liu Bang choose the dragon robe according to the rules of the Qin Dynasty. If Liu Bang belongs to fire, he can still make a yellow or red dragon robe. It looks normal, but Liu Bang is a wood. If he wears a green dragon robe, he will definitely stand out. Moreover, if the rules of the Qin Dynasty are completely changed, it is estimated that the three generations of the Han Dynasty can make up a traffic light, so Liu Bang later chose orange as the color of the robes, on the grounds that the sun shines on everything and the people themselves.

Third, I like golden yellow best. Therefore, the robes of the royal family in the Han Dynasty were not the golden yellow on TV. Generally, the robes of the royal family in the Han Dynasty are a little dark or a little red. Yang Di in the Sui Dynasty liked golden yellow and got a golden dragon robe, while the Tang Dynasty continued the rules of the Sui Dynasty, so he always wore a golden dragon robe. Later, other dynasties did not intend to change this rule, so it was handed down, and even royal items such as yellow vests continued.