To understand why ancient people have a definition of the size of the gate, we must first understand the ancient social environment.
Ancient times were backward in science and technology, society, economy and public security. In other words, if the ancient social phenomenon is put into modern times, it will be a hell on earth where people burn, kill and rob and commit all kinds of evils. Modern social life, put in ancient times, is a utopia on earth.
In ancient culture, the size of the door means the social orientation of this family. Only those rich and powerful people can build their homes tall and big. Ordinary people can't afford to build tall doors at first, but even if they do, they will be destroyed by some people who don't like them. Why destroy it?
Because? You're so shivering, why are you pretending to be a big-tailed wolf and your family is awesome? ? Others don't like your bullying, and you don't have the money and strength to bully, so you can only bow your head and accept the ridicule of others, even secretly.
To put it bluntly, in ancient times, if you didn't have the corresponding strength, then don't build your home too big, otherwise it will only bring disaster to yourself. So the size of the gate is said in geomantic omen. Too big will be said unlucky, too small will be said unlucky.
But in modern times, this statement no longer applies. Because modern public security is good. Even if you turn your door into a worse one, others will just take a look. You won't think your house is ostentatious, and you won't think you are here? A wolf with a big tail? No one will risk illegal imprisonment, because there is only one door for you. So in modern times, the city gate can be built as big as you like.