answer
Everything is empty, quiet and indifferent, detached and refined.
The theory of "emptiness" is the basic doctrine of Buddhism, and Wang Wei has a profound understanding of Buddhism through contact with Zen. "Emptiness" is the true nature of the world, and poets have a thorough understanding of Buddhism.
With the infiltration of Buddhism, poets became interested in expressing ordinary feelings. The "emptiness" in his poems expresses the emptiness of his mind with rich tone of voice and material state, and pushes the artistic conception of reality to a very wonderful realm.