When he arrived in China around about, I don't know, 500 AD, the Indian sage Bodhidharma was asked by Emperor Wu, "Who are you?"
Bodhidharma famously replied, "I don't know."
Many people, including myself, have misunderstood this answer. Was he oblivious to who he was? Was he somehow being humble? Was he just trying to pull the rug out from under the Emperor? In any event, Wu didn't understand either, and Bodhidharma was lucky to get out of there with his head still on his shoulders.
Recently, while we've been talking about buddha-nature during Monday Night Meditation, I've come to a new (at least for me) understanding. Buddha-nature, of course, is more than just something that all sentient being have - all sentient beings completely are buddha-nature. And since we're all of the same substance, there's no differentiation between any two sentient beings - we're all one. And since buddha-nature encompasses more than just sentient beings but all phenomena, too, everything is buddha-nature and everything is everything - it's all nothing but buddha-nature. That "all phenomena" also includes our thoughts, memories, mental maps and models, ideas, concepts, and so on. And since those are a mere part of the seamless whole of buddha-nature, by definition buddha-nature itself goes beyond any concept we might have of what it is. However we try to wrap our mind around it, we're still limiting it to "it's this" and "not that." Whatever we think it is, it isn't. It's beyond, it transcends, any concept of what it is.
Okay, got all that? Good. Everything is everything, and in the absolute sense, nothing is separate from anything else and therefore nothing exists individually. But that's not how we experience the world. In this relative world, I am me and you are you, mountains are mountains and rivers are rivers. I can see them, I can identify them, I can describe them to others and get separate confirmation that these things exist. But in the absolute sense, it's all buddha-nature, all part of a seamless whole, and it's only the mind that tries to subdivide the true fabric of reality into separate "things." We can directly experience the absolute in a deep state of meditation - when the "thinking mind" finally stops its chatter and clams down, it also stops subdividing everything into separate "things," and we can experience the absolute. But as soon as a thought arises, even, "Ah, so that's what the absolute is," we fall right back into the world of the relative.
So meanwhile, back in China, Emperor Wu asks Bodhidharma "Who are you?" His question is "stuck" in a relative mind-set - he's really asking "Of the millions of separate individuals out there, none of whom, incidentally, are me, which one are you and how do you fit in?"
Bodhidharma answers not from the relative, but from the absolute. Why? Perhaps to test Wu to see if he understands the difference (if so, Wu failed the test). Perhaps to teach the Emperor, by showing him another way of seeing the universe. Or perhaps, and I don't think this is the case, because Bodhidharma abode in the absolute and saw things only from that perspective.
In any event, the absolute answer to the relative question, "Who are you?" is that we are all buddha-nature, we are all that which transcends even our own understanding or conceptualization of what it is. We are beyond our "knowing" or, for that matter, our "not-knowing." Bodhidharma's answer, "I don't know" means that he absolutely does know (pun intended), but further knows that it's beyond the realm of words and thoughts.
He gives an absolute answer to a relative question. Five generations of teachers and students later, a monk approaches the Sixth Chinese Patriarch Hui-Neng to begin his study under him as his teacher. Hui-Neng asks the monk, "What is this that comes thus?"
Hui-Neng knew that the monk knew the story of Bodhidharma and Emperor Wu, and wouldn't fall into the trap of blurting out a casual answer to "Who are you?" without showing off his learning, so he surprises him by asking essentially the same question ("What is this that comes thus?" is basically "Who are you?"), but posing the questions from the absolute perspective rather than the relative. "What?" instead of "Who?" "That which comes thus" acknowledges things just as they are, without underlying presumptions or conceptions.
The monk thought about the question for eight full years, and then came back to Hui-Neng and said, "Now I understand your question, 'What is this that comes thus?'." Hui-Neng asks him how he understands this.
The monk replies, "To describe a thing misses the mark."
Hui-Neng suspects that the monk understands, but to test him he asks, "Does your answer rely on your practice and experience?" He might understand that what comes thus is buddha-nature, but does he understand that even his practice and experince are buddha-nature, too? Is his mind free of some things, but still sticking to others?
The monk says, "It is not that there is no practice and experience, but to taint it with words is impossible."
Bulls-eye! He got it! In confirmation, Hui-Neng comfortably slips back into the relative perspective, and tells him, "I am like that, you are like that, and the buddhas and patriarchs of India were also like that."
All things are buddha-nature, and all things are therefore "empty" of a separate, individual existence. This is the absolute view. But it doesn't feel that way to us, and we experience the world in a relative sense - "self" relative to "others," "this" relative to "that." One view isn't "right" and the other "wrong," it's just two different ways of looking at things. The enlightened mind can hold both views simultaneously without sticking to one of the other.
You can hold both views simultaneously yourself without sticking to one or the other by practicing meditation - calming the mind, stopping the discriminating thoughts that try to separate things out from each other, and engaging in shikantaza ("just sitting"). You will discover the state of practice-enlightenment and abide in that state - at least until the bell rings ending the meditation period.