To my thinking, the most profound of the Buddha's purported utterances was this (I paraphrase): "I attained absolutely nothing when I attained absolute enlightenment; that is why it is absolute enlightenment."
Nearly every mystical tradition essentially tells us the same. "Realization" is a coming to realize in conscious experience what is already true of us. Nothing is gained. Nor does it matter or is it necessary, were it possible, to know what that "true of us" is. If those who 'know' do not speak, it is because there is nothing to say. Those who speak because they 'know' might know, but they do those who do not know a great disservice. What is known is grasped, what can be known is grasped for. But striving to be is a denial of what is.
Unity cannot be achieved because it already is. If it were not, there would be no such thing, actual or possible. Is there Unity? How could it be otherwise? To say this does not imply something redemptive, spiritual or purposeful. If the One were Zhuangzi's "Great Clod", then that would be our Unity. The realization of Unity is not a ticket to heaven or a guarantee of meaning; it is a subjective experience of release into nothing defined.
Yet it is believed that one can "realize" Unity; something transformative happens and the reality of that Unity informs one's conscious life in its entirety. For this, we can strive. But is striving an effective means? This is where Zen steps up and shouts, "No!" To do so would be for one to search for his head because he could not see it, or to look for a head to put on top of one's head. Nevertheless, a great deal of striving accompanies Zen.
I have my means, though I won't presume to call it "effective". I have not "realized" Unity. My effort to do so is to simply accept in the moment that it is so, whether realized or not. Yes, I will say it again: There are no conditions to meet; it is already true in me and in you. What need to strive? What need to speak of failure? What need to self-condemn? What need to realize anything? There is absolutely no gap between anything and everything.
Again, Unity with what? There is no 'what', nor any need for 'what'. But let us call it, like Zhuangzi, "The Great Openness", "The Great Thoroughfare", "The Great Transparency" — all of which speak of experience without content and not of some 'thing'. The way of Zhuangzi is not to realize the Truth, but to realize no need for Truth. "It is just being empty, nothing more." (Zhuangzi, 7:13; Ziporyn)
You can check out Scott's writings on Zhuangzi here.