So what happens if you withdraw attention from the objects in space and become aware of space itself? What is the essence of this room? The furniture, pictures, and so on are in the room, but they are not the room. The floor, walls, and ceiling define the boundary of the room, but they are not the room either. So what is the essence of the room? Space, of course, empty space. There would be no "room" without it. Since space is "nothing," we can say that what is not there is more important than what is there. So become aware of the space that is all around you. Don't think about it. Feel it, as it were. Pay attention to "nothing." As you do that, a shift in consciousness takes place inside you. Here is why. The inner equivalent to objects in space such as furniture, walls, and so on are your mind objects: thoughts, emotions, and the objects of the senses. And the inner equivalent of space is the consciousness that enables your mind objects to be, just as space allows all things to be. So if you withdraw attention from things—objects in space—you automatically withdraw attention from your mind objects as well. In other words: You cannot think and be aware of space—or of silence, for that matter. By becoming aware of the empty space around you, you simultaneously become aware of the space of no-mind, of pure consciousness: the Unmanifested. This is how the contemplation of space can become a portal for you.

Eckhart Tolle

from The Power of Now: A Guide to Spiritual Enlightenment