Wudai means non-dependence, and plays a central role in Zhuangzi's philosophy of liberation. When we depend on absolutely nothing, we are free. Yet how is this possible? It is utterly impossible if we think it means that we are not in fact dependent on myriad things, both physical and social. So, non-dependence is a matter of attitude, not of 'fact'. This attitude might be represented by a number of words, but for my purposes here, I will choose 'happiness'. One is non-dependent, and therefore free, when one's happiness depends on nothing.
I depend on my beating heart to keep me alive. I do not require a guarantee that I be kept alive to be happy. It is not that I do not depend on my heart beat to live, but that my inner life is not dependent on the external to rest in happiness.
The first chapter of the Zhuangzi is where this case for non-dependence is most forcibly made, but it is implicit throughout the Inner Chapters. Zhuangzi first makes the case that we are all equally dependent. The vast bird Peng, who must ascend to forty thousand feet to get enough air under its wings to make its journey to the Southern Ocean, is no less dependent than the quail who only requires a few feet for its comparatively short glide from tree to tree. No one is any less dependent than anyone else, (Mr. Romney).
Having established this, Zhuangzi goes on to show how we can be 'spiritually' free of all dependence so as to partake of "free and unfettered wandering". He gives a number of examples. If we allow ourselves to be inwardly dependent on our external successes and the esteem of others that ensues, we shackle ourselves. If our happiness requires that we should 'succeed', then unhappiness looms just over the horizon. If we are happy because we are well and fortunate, unavoidable misfortune and ill health will kill that happiness. But then we were never truly happy in the first place, for true happiness cannot co-exist with fear and anxiety.
A certain sage saw through this folly of dependence on the external and declared that one's self-esteem should rest on one's esteem for one's self alone. But Zhuangzi asks if this is not just another form of dependence. Self-esteem is a form of moral discrimination, and except perhaps in the case of megalomania, must certainly fail. Yet, since self-esteem, negative or positive, is an unavoidable attribute of the egoic-self, only through transcendence of that self is non-dependence possible. This is possibly the hardest nut to crack.
But wait; can we not apply the principle of non-dependence even here? Must we depend on some 'spiritual success' for our happiness, or can we not even depend on that? Is 'perfection' a prerequisite to happiness, or is the whole point that nothing need be prerequisite? Freedom and happiness are always just and only an attitude away. Can we be non-dependent in the midst of our dependence? Is it ever anything else but precisely this? Does our happiness even depend on being happy? It is dependence to think we must be anything other than who we presently are. Wudai is not achieved; it is simply realized in “handing it all over to the unavoidable”, in trustfully releasing oneself into vastness.
You can check out Scott's writings on Zhuangzi here.