Chapter 11
第十一章
The thirty spokes unite in the one nave; but it is on the empty space (for the axle), that the use of the wheel depends.
三十辐共一毂，当其无，有车之用。
Clay is fashioned into vessels; but it is on their empty hollowness, that their use depends.
埏埴以为器，当其无，有器之用。

The door and windows are cut out (from the walls) to form an apartment; but it is on the empty space (within), that its use depends.
凿户牖以为室，当其无，有室之用。
Therefore, what has a (positive) existence serves for profitable adaptation, and what has not that for (actual) usefulness.
故有之以为利，无之以为用。