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. clay is fashioned into vessels; but it is on their empty hollowness, that their use depends. 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. therefore, what has a (positive) existence serves for profitable adaptation, and what has not that for (actual) usefulness.

三十輻，共一轂，當其無，有車之用。

埏埴以為器，當其無，有器之用。

鑿戶牖以為室，當其無，有室之用。

故有之以為利，無之以為用。

【译文】

三十根辐条汇集于车毂而造车，有了其中的虚空，才发挥了车的作用；糅和陶土制作器皿，有了器皿内的虚空，才发挥了器皿的作用；开凿门窗建造房屋，有了门窗四壁内的虚空，才发挥了房屋的作用。所以，"有"之所以能给人以便利，是因为它营造的"无"发挥了作用。