In this way, wholeheartedly embody the endlessness and roam where there is no sign, fully realize what is received from Heaven, but without thinking anything has been gained thereby. It is just being empty, nothing more.
For the most part I have previously left this description of Zhuangzi's mystical vision to speak for itself, thinking it will either find resonance with the reader or not. There is also the fact that I, the writer, can honestly only guess at what this fully entails. Yet I speak often of "inklings" and "approximations" because I think Zhuangzi's mysticism is largely facilitated by what I call "imaginative meditation". To my reading, Zhuangzi does not seem to advocate an instantaneous 'enlightenment', but rather the steady cultivation of a radical transformation of one's point of view. Thus we can speak of an incremental realization of the experience he describes here. I may be wrong; but though it is important to try to get it 'right', in the end it is only our individualized use of his teaching that matters. In the end, Zhuangzi's way is to encourage us to experience our own.
"Endlessness" is clearly a word that points at something that cannot be put into words. We have a large array of such words — infinity, eternity, omnipresence — none of which, strictly speaking, can be said to supply a mental image that is anything more than a testimony of their inability to accomplish what words are intended to do. But this is precisely what makes them so powerful should we wish to let them be so. They are an invitation to go beyond words, beyond the "understanding consciousness". This is really all that Zhuangzi suggests we do. Only he would have us go beyond merely thinking about them to a place of actually "embodying" them. How is this possible?
"It's just being empty, nothing more." Empty of what? Empty of our sense of being a fixed identity. But though something must "go", it is only a mental construct in any case; nothing is "lost"; nothing could ever be lost. Thus, though we might see this as the negating side of this mystical experience, it is never other than totally affirming. "Release" and "surrender" are words that suggest this. Sweet surrender.
But still we ask "how?" I have suggested my answer; but the only general answer, from a Zhuangzian perspective, is probably something more like "however you wish." Perhaps the most important thing of all is that the process be the "embodying"; for the whole point is to live happily, not to gain some necessary end.
You can check out Scott's writings on Zhuangzi here.