This sentence comes from Chai Lu written by Wang Wei in the Tang Dynasty.
Chai Lu
Original text:
No one can be seen in the silent valley, only the voice is heard.
The shadow of the sunset shone into the depths of the forest, and the scenery on the moss was pleasant.
Translation:
There is no one in the silent valley, only the voice can be heard. The shadow of the sunset reflected into the depths of the forest and shone on the moss in the dark.