三十辐共一轂，当其无，有车之用。埏埴以為器，当其无，有器之用。凿户牖以為室，当其无，有室之用。故有之以為利，无之以為用。

Tao Ching Chapter Eleven

Thirty spokes unite around one hub to make a wheel.

It is the presence of the empty space that gives the function of a vehicle.

Clay is molded into a vessel. It is the empty space that gives the function of a vessel.

Doors and windows are chisel out to make a room.

It is the empty space in the room that gives its function.

Therefore, something substantial can be beneficial.

While the emptiness of void is what can be utilized.