What Realm Does the Echo in the Valley Belong To?

When you shout in a valley, this sound is the fundamental state. When the fundamental state encounters air or rock walls and meets obstruction, the transmitted sound becomes altered, for the four fundamental elements undergo change. When we hear the echo, it feels relatively illusory and unreal, as if coming from a distant horizon, greatly differing from the human shout. The human shout is real, while the echo arises subsequently based on the shout, much like the second moon.

The echo resembles a rebounded sound encountering obstruction, similar to a ping-pong ball bouncing off a paddle—the speed of the rebounded ball depends on the magnitude of the resistance it encounters. The volume and quality of an echo in an empty valley depend on the intensity of the air currents and the resistance of the rock walls. The more expansive the valley, the more false, illusory, and unreal the echo becomes. The echo in the valley cannot be said to be real, nor can it be said to be false; it possesses a nature of being neither entirely real nor entirely illusory, for it carries the quality of the fundamental state.

The second moon directly originates from the true first moon in the sky. Without the first moon, there would be no second moon. You cannot claim the second moon is real, nor can you claim it is false. The second moon possesses a nature of being neither entirely real nor entirely illusory, for it carries the quality from the fundamental state of the first moon—indeed, it carries a significant amount—thus appearing relatively real. Nevertheless, a wise person, upon pointing at the second moon, must not mistake it for the true first moon. Similarly, one must not mistake the echo in the empty valley for the true sound of a person; one can only trace back along the echo to find the true sound of the person, thereby locating the individual. This is also the secret to Chan meditation.