Wet, cold, Yin and other harmful gases to human atmosphere are generally in the wild mountains and ridges, in the old houses which are uninhabited all the year round.

Take residence as an example.

When a house is normally occupied, you don't feel anything wrong, because the house is popular at this time.

But when the owner moves out of the house, over time, you will find that grass grows on the walls and roofs, and the house ruins very quickly.

When people live, they don't go to the roof to pull weeds, but then the weeds will not grow. After people leave, how can they grow grass?

When you...