In teaching emptiness there is nothing material to show, nothing to produce. So how do we talk about emptiness? It has to be based on experience. It has to be a sharing of experience. As far as my experience of emptiness goes–I have some, a very little. I’ll just be explaining a little of my experience, like an introduction pointing out the sights on a mountain. Just a brief introduction to that subject.
Emptiness is a little bit like talking about space. What if somebody asked you, “What is space? What is space like?” If you had to say, “Space is like this and that,” it is rather difficult to explain, isn’t it? There is nothing, no color, no shape to describe if you are trying to describe space. Is it triangular, cubical, or spherical? You might have some other way to explain it. So emptiness is a matter of experience and understanding.
Written by Khenpo Karten Rinpoche in the book Precious Teachings, the chapter entitled “Sunyata, Essence of Mind” page 94 in the paper copy, and page 101 of the PDF version.