"Thirty spokes will converge in the hub of a wheel; But the use of a cart will depend on the part of the hub that is void.

With a wall all around a clay bowl is molded; But the use of the bowl will depend on the part of that bowl that is void.

Cut out windows and doors in the house as you build; But the use of the house will depend on the space in the walls that is void.

So advantage is had from whatever is there; But usefulness rises from whatever is not."