11:6.3

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.

We look at it, and we do not see it, and we name it 'the Equable.' We listen to it, and we do not hear it, and we name it 'the Inaudible.' We try to grasp it, and do not get hold of it, and we name it 'the Subtle.' With these three qualities, it cannot be made the subject of description; and hence we blend them together and obtain The One. Its upper part is not bright, and its lower part is not obscure. Ceaseless in its action, it yet cannot be named, and then it again returns and becomes nothing. This is called the Form of the Formless, and the Semblance of the Invisible; this is called the Fleeting and Indeterminable. We meet it and do not see its Front; we follow it, and do not see its Back. When we can lay hold of the Tao of old to direct the things of the present day, and are able to know it as it was of old in the beginning, this is called (unwinding) the clue of Tao.

The (state of) vacancy should be brought to the utmost degree, and that of stillness guarded with unwearying vigour. All things alike go through their processes of activity, and (then) we see them return (to their original state). When things (in the vegetable world) have displayed their luxuriant growth, we see each of them return to its root. This returning to their root is what we call the state of stillness; and that stillness may be called a reporting that they have fulfilled their appointed end. The report of that fulfilment is the regular, unchanging rule. To know that unchanging rule is to be intelligent; not to know it leads to wild movements and evil issues. The knowledge of that unchanging rule produces a (grand) capacity and forbearance, and that capacity and forbearance lead to a community (of feeling with all things). From this community of feeling comes a kingliness of character; and he who is king-like goes on to be heaven-like. In that likeness to heaven he possesses the Tao. Possessed of the Tao, he endures long; and to the end of his bodily life, is exempt from all danger of decay.