The heart of Cook Ding's lesson in how best to nourish one's life (as seen in his 'undoing' of an ox) is to be found in the manner in which his knife becomes thickless and the ox full of spaces. "In those joints there-exists spaces, and in this knife blade there-exists-no thickness. With no-existence of thickness to enter the existence of spaces — the spacious, spacious-ly for its roaming about the knife, there must, of course, exist more than enough ground," reads Wu's very literal translation (his italics; bold for the characters themselves). The thickless knife finds more than enough space in the "inherently-so" nature of an ox carcass so as to pass through it without harm.
The message seems clear enough: If we wish to negotiate ourselves through life without harming ourselves or others, we need only become similarly thickless; when thickless, the world will open up before us and our path will be clear.
Commentators debate about what this thickless knife represents. Some suggest Dao; others self. But, though both are probably true, to call it either is to give it thickness. To be thickless, it cannot be an objectified anything. Cook Ding, his knife, and the ox have become one, and this is experiential dao. They are all four thickless in their unity.
"It's just being empty, nothing more," Zhuangzi concludes in his seventh chapter. This is to be thickless; and when we are thickless, all the world is likewise thickless, which is to say, it is infinitely spacious. Thicklessness beyond thickness is openness. Open to everything that arises, all that arises is upon to us.
But what about the poor slaughtered and now butchered ox? It is being dao-fully "undone" by Cook Ding because he has already "undone" himself. He could hack and chop it, which would indeed be unholy butchery. Instead, he honors it by undoing it as it presents itself to be undone, and this because he is simultaneously undoing himself. His deconstruction of the ox is an echo of his deconstruction of himself; they are one as mutually participating in the cycle of construction and deconstruction. Faced with an especially knotted bit, Ding stops, concentrates, loses himself and . . . thump, a piece of ox thicklessly falls to the thickless ground with which it is one, and therefore belongs.
Having a life to live and nourish, we wield the knife. Yet we, too, receive it into our own lives, opening up spaces for it, awaiting the final thump as the most natural thing in the world.
Or something like that.
You can check out Scott's writings on Zhuangzi here.