Tulku Urgyen Rinpoche says : “This buddha nature of ours, which is primordially free from the two extremes of being and not being, is described with the word ‘unity’.
What does unity mean in this context?
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 can’t, because it’s empty of all identity, right?
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.”