Does this sentence make sense? Let's break it down and see.
You = the original mind, the True Self. Nothing else can hear me when I speak and reply in turn. There is no other "you." When I speak to you, I speak to that which can hear, understand, and reply. (Although this statement sounds axiomatic, and is in fact straightforward and undeniable, it is also profoundly mysterious and, not to mince words, awe-inspiring. In ancient Chinese Zen and also in Taoist meditation there was a "direct investigation" method, whereby one engaged in a sustained effort of mentally searching inside one's body for the "Old Master." Taking a seat in a quiet place, or lying down flat in a dark room, one systematically turns one's whole attention toward each aspect of the body in turn, closely investigating the breathing, pulse, heartbeat, skin, eyelids, pores, bones, &c to find the location of this "solitary one that I am." Can this "Great Sage" be found anywhere in the scope of what is accessible to awareness? If not, what does it mean? Actually, Shakyamuni Buddha also taught this direct investigation method in the oldest Pali Suttas, and an even more refined version for each of the senses in the Shurangama Sutra.)
Are = A form of the verb "to be," therefore Being. The Being that is you. The ancient Indians said, Tat Tvam Asi, or Thou Art That. (Everybody thinks they know what "Being" is already, but when you try to articulate it exactly, you are "just like a dumb man trying to recount an amazing dream." Many books have been written trying to find out how to even ask "the question of Being." It seems that while "beings" seem to appear with certainty, the Being of beings -- the matrix they spring out from -- is dark and obscure, impenetrable to language.)
Not = The entry of an absolute negation. The emergence of basic contradiction. Here language seems to run into an impassible barrier. In trying to find Being, it finds only what it is not! But as this "not" functions in the sentence we are breaking open, it modifies rather than standing opposed to the word "are." It suggests the way your Being be-s this right here now rather than that or the other, somewhere elsewhere at another time, which brings in the mysterious element of "time" and also the difference of "things in space." Yet, how can a being not be? A deep mystery, this "Not!"-- like Joshu's "Mu," or the Vedantic "Neti Neti." This pencil, here on my desk, is not the pencil on your desk. They are both pencils, yet one is not the other. This pencil is not that pencil, yet both pencils share a certain identity, since they are both obviously pencils and not crayons. It's with this "Not" that the possibility opens of you not being what you claim to be, not at all like that other person over there, or maybe just would like to and maybe will someday become. You're not Buddha, you're just a dog! It's with the emergence of the "not" that Being itself seems to plunge into chaotic oblivion, ceasing to be itself. What a steep decline! What a drastic fall! And imagine my savagery in imprinting on you this seal of ultimate dismissal, this ensign of total ruin and catastrophe! The demons enter, and dance wildly as demons do.
Enlightened = Lit up, out in the open, immediate, accessible, real. Your Being in the sense of mindedness, heart, xin, is hidden from me. Yes, I can instantly see your body, your eyes and skin and hair, I can hear your words and read what you write and argue against your opinions, all this is out in the open, but the deepest mystery of you which is your awareness, the very taste of your own Being, is obscure and totally impenetrable to my perception. Yunmen says, "Everyone has this same radiant Light -- so when you try to look directly into it, why is it dark and obscure?" Why does Yunmen say, then, that everybody has the radiant light?
Indian Buddhism, like the ancient Vedas, came up with the notion that there is only one consciousness, one pure and radiant light. According to this idea, the differences between you and I are trivial and insignificant when compared to our basic mysterious sameness. Bodhidharma said, "You ask me a question. That's Mind in you. I reply. That's Mind in me." All that appears appears in and by this Light. So, any appearance is a direct function of the mind-essence, which is "root-Bodhi" or original enlightenment. It is in this sense that "Enlightenment is all there is." The sky allows many things to appear, but it is always just the sky. So perhaps instead of saying that this or that person is enlightened or not enlightened, we should say rather that people are or are not awakened to their originally enlightening mind-essence.
Zen is cutting off thought-discriminations and seeing It directly. Seeing what? The sky of reality itself. So what is enlightenment? What is "not enlightenment"? It seems that everything arrives already enlightened. And Mind itself does all the enlightening, since it is the Light itself. Seeing is It, so is hearing. Wake up instantly to This!