Why do people in history have to "get married" in a figure of eight? What is the metaphorical meaning behind it?

In recent years, costume drama can be said to be a fire. For example, this year's "Do you know it should be green, fat, red and thin?" A few years ago, there were "Lonely World" by Hu Bingqing and An, and "Calculation of Beauty" by Ruby Lin and Yang Mi. We are usually attracted by wonderful plots, but few people notice that in TV series, the first step for a man and a woman to get married is for the matchmaker to get their eight-character wedding cards and then close them to see if they can be closed. So why did ancient people have to match their personalities when they got married?

First of all, because the ancient feudal system had great constraints on women, women were not allowed to leave their homes or contact men outside their homes alone before marriage, otherwise they would be suspected of giving and receiving in private. In this way, one of the married couples is trapped in the inner room and the other is blocked out of the inner room, so it is completely impossible for both men and women to try to understand each other's personality as they are now. Therefore, they can only believe the story of birthday.

Secondly, the ancient feudal society was underdeveloped in science and technology. In order to rule the people, ancient kings widely promoted Taoism and claimed to be the son of heaven, so they were called emperors. Therefore, ancient people believed in matchmakers and divination. So they really believe what birthdays say.

Finally, the date of birth is actually based on it, and it is not fabricated out of thin air for no reason. Presumably, everyone knows the sixty-four hexagrams of Yijing, which is the gossip of Taiji. Yes, the birth date is also counted as some hexagrams in the Book of Changes, so there is some truth to follow. Therefore, the date of birth also has certain reliability. So people in history must have got married in a constellation.