How do we describe buddha nature? Buddha nature is said to resemble space. Can we say that space exists? Can we say that it doesn’t? We cannot, because space itself does not comply with any such ideas. Concepts made about space are merely concepts. Space, in itself, is beyond any ideas we can hold about it. Buddha nature is like this. If you say that space exists, can you define it as a concrete existent entity? But to say there is no space is incorrect, because space is what accommodates everything — the world and beings.
Right now, visual forms, sounds and smells and so on are all present in our experience. If buddha nature were nonexistent, there could be no such experiences taking place. But if we say buddha nature does exist, then what is it that experiences? Can you pinpoint it? You cannot, because it is empty of all identity. Thus, there is no confining these two — perceiving and being empty. While perceiving, buddha nature is empty of a perceiver; while being empty, there is still experience. Search for the perceiver; there is no “thing” to find. There is no barrier between the two. If it were one or the other there should either be a concrete perceiver who always remains, or an absolute void. Instead, at the same time vivid perception takes place, that which perceives is totally empty. This is called the unity of experience and emptiness, or the unity of awareness and emptiness. The fact of experience eliminates the extreme of nothingness, while the fact that it is empty eliminates the extreme of concrete existence.
In this way, we can say that existence and nonexistence are a unity. This unity is not something we can devise intellectually, which is why it is called the “view beyond concepts.”
–Tulku Urgyen Rinpoche