The basic principle of Yin Zhai Feng Shui is an environment that can gather the field energy of the sun, the moon, the stars and the five elements (in Feng Shui theory, it is an effective combination of shape, potential, reason and qi).
The most important thing is to embrace mountains and rivers. The mountain ring can gather the field energy of the sun, the moon and the stars (like a satellite receiving antenna shaped like a pot cover), and the water hug is also surrounded by water to gather the field energy (the so-called "gas dispersed with the wind, the boundary water stops"). In other words, the five-element field of the sun, the moon and the stars can gather water along the mountains. The so-called cave center is the focus of the five-element field, but the surrounding landscape can't be as regular as the satellite signal receiver, so it is not so easy to find its focus.
The only sign of the heart of the cave (the only sign of the land of geomantic omen): Because the soil that has been focused on this focus for many years will produce obvious color changes, it is impossible for any living animal to survive in this focus, and even the roots of plants can't exist (even if there are, they are already burnt), let alone any other treasures. This is the real acupoint.
How to discover this is the teacher's skill. If you want to know, you must learn from the teacher.