Looked at from the point of view of their differences, even your own liver and gallbladder are as distant as Chu in the south and Yue in the north. But looked at from the point of view of their sameness, all things are one.
(Zhuangzi 5:5; Ziporyn)
Zhuangzi makes quite clear what all things have in common: their transience. In the context of this particular passage in which ‘Confucius’ explains how it is that a “one-legged ex-con” is a great sage he says: “He looks on the alterations of all things as his own fate, and thus holds fast to their source.” He has in effect identified himself with ever-evolving and unfixed. To truly do so would require, it would seem, the release of one’s attachment to a fixed-identity. I prefer Mair’s translation of this sentence, though they both make essentially the same point: “He realizes that evolution is the destiny of things and thereby maintains what is essential.”
Though he never explicitly says so, since it was probably not even a culturally relevant concept, I think Zhuangzi would dismiss any concept of a ‘soul’ as distinctly counter-productive. A ‘soul’, an identity that survives death, is most certainly a fixed-identity and is, to my thinking, the core delusional belief arising out of the evolution of human consciousness. This is not all that surprising; I, for my part, wouldn’t mind having one if that did not also mean that I had one to ‘lose’. But we don’t have to reflect much on the nature of things to realize that things just aren’t as we would have them to be. Daoism is in many ways an accommodation with this reality rather than an attempt to subvert them.
In order to get a sense of this transience which we share with everything else, I like to think of those human beings so long departed as to be utterly forgotten. What do an ancient pharaoh and his most abased subject have in common? The only thing that can honestly be said of them: they are no more.
Yet we should not overlook the fact that none of this is in any way intended to denigrate things presently extant. To declare that “all things are one” is to affirm each and every one of them as the things that they presently are. Without things, what ever-transforming reality is there? The “all” is ever much as important to apparent reality as the “one”. Nor need we think that this declaration of reality as the ever-transforming is the final word. It is all just a wonderful Mystery, after all.
You can check out Scott's writings on Zhuangzi here.