Why did ancient people regard "mountain south and water north" as yang, and "mountain north and water south" as yin?

This statement mainly exists in the northern hemisphere. For details, see "The Foolish Old Man Moves the Mountain": it refers to the southern part of Henan and reaches Hanyin. "Climbing Mount Tai": The yang of Mount Tai is that the Wen River flows to the west; its yin is that the Jishui River flows to the east. "Travel to Baochan Mountain": The so-called Huayang Cave is named after the Yang of Huashan Mountain. 1. Mountains to the south and water to the north are all Yang, and mountains to the north and water to the south are all Yin.

2. Yang refers to the side that sees the sun, and yin refers to the side that cannot see the sun. The ancients called the side that sees the sun south. The mountain is higher than the ground, and the back side (i.e. the north) cannot see the sun, so the south side of the mountain is yang and the north side is yin. Water refers to the river. The river is lower than the ground, and the side that sees the sun is in the north, while the south side does not get sunlight, so the north side of the water is yang and the south side is yin.

3. Geography: The middle reaches of the Yellow River are north of the Tropic of Cancer. There is no direct sunlight all year round. The sun only shines from the south, so for mountains, the south side of the mountain can be illuminated by the sun. , that is, the sun is yang; the north is yin. On the contrary, in terms of water (river), since the terrain is high in the northwest and gradually lowers in the southeast, due to the influence of geostrophic deflection force, rivers flowing eastward will tend to flow in the southeast direction when flowing, and the south bank is more susceptible to river erosion. In Xia Tao, the south bank has a relatively large height difference, the terrain is low and humid, and it is difficult to get sunlight under the bank; the opposite is true for the north bank. Therefore, for water systems below the ground level, the sun will not shine on the south bank of the river, but only on the north bank. Therefore, the north of water is yang, and the south of water is yin.

The south of the mountain is yang and the north is yin, because the two places are affected by solar radiation differently. Water in the south is yin and water in the north is yang. This is because the south bank of the river is wetter than the north bank due to the influence of the earth's rotation. Since most of our country is located north of the Tropic of Cancer, the direct sun point is always south of the Tropic of Cancer. Sunlight mainly shines from the south to the north. The south slope is a sunny slope, and the south can get more solar radiation and heat. . Therefore, the south of the mountain is yang, and the north of the mountain is yin. At the same time, the river is affected by the deflection force of the earth's rotation, and the river will deviate to the right bank when flowing. However, most rivers in China flow from east to west. The south bank (right bank) of the river is easily affected by the impact and erosion of the river water, resulting in a situation where the south is wet and the north is dry. . Therefore, the north of water is yang and the south of water is yin.