Mind is what thinks: “I am, I want, I don’t want”; it is the thinker, the observer, the subject of all experiences. I am the mind. From one point of view, this mind does exist, since I am and I have a capacity for action. If I want to see, I can look; if I want to hear, I can listen; if I decide to do something with my hands, I can command my body, and so on. In this sense, the mind and its faculties seem to exist.
But if we search for it, we cannot find any part of it in us, not in our head, our body, or anywhere else. So from this other perspective, it seems not to exist. Therefore, on the one hand, the mind seems to exist, but on the other, it is not something that truly exists.
However exhaustive our investigations, we will never be able to find any formal characteristics of mind: it has neither dimension, color, form, nor any tangible quality. It is in this sense that it is called open, because it is essentially indeterminate, unqualifiable, beyond concept, and thus comparable to space. This indefinable nature is openness, the first essential quality of mind. It is beyond illusory consciousness that causes us to experience mind as a “me” possessing characteristics we habitually attribute to ourselves.
But we must be careful here! Because to say mind is open like space is not to reduce it to something nonexistent in the sense of being nonfunctional. Like space, pure mind cannot be located, but it is omnipresent and all-penetrating; it embraces and pervades all things. Moreover, it is beyond change, and its open nature is indestructible and atemporal.
~ Kalu Rinpoche