This should start with the past building structures and building materials. As we all know, the former houses were adobe walls of huts, and the better ones were wooden houses, like brick houses. It would be nice to have one or two families in a village, mostly local landlords and gentry. Building materials like this, except bricks and tiles, are not strong, and the most feared thing is the wind and rain. And the "two trees" here are not two trees, but empty fingers, which means there are trees on both sides of the house.
As we know, there were many trees in the past, and there were two biggest problems in building houses by trees: First, the branches of big trees were thick when they encountered storms, and it was easy to wash away those huts and earthen houses. The second is the root. With the growth of years, the roots will be deeper, wider and stronger. The strength of the roots can be imagined. In the past, the foundations of houses were shallow, which easily caused "family destruction".
Therefore, there is a saying that "two trees are sandwiched in one house, and the family is ruined." Brick and tile houses have a solid foundation and strong materials, so they are not afraid of this. Most people who can build brick houses are rich and powerful, so there is also a saying that "two trees are sandwiched in one house, and gold and silver are full." Because there are few gentry after all, this statement is not widely circulated.
Besides, "two trees in one room, gold and silver are full early." This proverb should be invented by people who have never lived in mountainous areas. If there is a problem with life safety, where will there be a "house full of gold and silver"?