In the first chapter of the anthology Hiding the World in the World (Scott Cook, ed.) Harold Roth makes his case for what he calls "bimodal mystical experience" as that practiced by Zhuangzi. Building on Walter Stace's model of two types of mystical expression, "intravertive" and "extravertive", he suggests that Zhuangzi's unique approach advocated both. Intraverted mysticism seeks union with the Ultimate and typically does not concern itself with the mundane. Unfortunately, he does not explain what is meant by extravertive mysticism except as practiced by Zhuangzi in his "going along with the present this". From this we can presume that it is a mysticism that is intended to be fully engaged in the world. Roth then affirms Lee Yearley's description of Zhuangzi's mysticism as "intraworldly" (in Mair; Experimental Essays on the Chuang Tzu); it is the expression of inner mystical experience in the actual world. I extend Zhuangzi's "Walking Two Roads" to include just this; one's intravertive mysticism informs one's manner of being in and responding to the world; the two can in no way be separated.
Roth has difficulties with Yearley's definition of the intravertive side of Zhuangzi's mysticism, however. Yearley says, "One neither attains union with some higher being nor unification with the single reality. Rather, one goes through a discipline and has experiences that allow one to view the world in a new way." In this, I agree with Yearley. So does Roth, but he wants something more. Although he firmly states that Zhuangzi's mysticism is innocent of having an "objective referent", still he would have a "continuously moving unitive force that can be merged with". For my part, I fail to see how this does not amount to the same thing as an "objective referent". The question is, is this an achievement of a purely personal realization of one's own human capabilities, the ability to set oneself free from evolved norms, or is it facilitated by union with a Something external to oneself? My sense is that the latter is completely alien to the philosophy of Zhuangzi.
Does it matter? None of it matters if we are not engaged in some process of mystical attainment. And it does matter if that engagement is patterned after a way of utter not-knowing, where the absence of ultimate verities becomes the impetus to the act of surrender into Mystery.
You can check out Scott's writings on Zhuangzi here.