Because in ancient times, many people used mud or huts to build their houses, so the houses they built would not be like BBK, and the houses built in this way would show a downward depression. In this case, the hut can easily lead to mud pits or air circulation, which can easily lead to the breeding of bacteria or diseases, which is very unfavorable to the family and people's health.
In ancient times, there was actually a saying that this building style is a specific and special statement, which is conducive to promotion and wealth in the future. Therefore, in ancient times, building a house step by step was actually a feng shui statement.
At the same time, in ancient times, people were very used to the trend from low to high, because we have a saying that people go up and water flows down, so people have to go up to have a good momentum. This is also the thought and thinking of ancient people, and it will also give people a psychological hint, so this sentence is quite reasonable.