In the mountains, we see a valley covered by a sea of white clouds. The surface of the clouds gleams, immaculate. We start to walk toward the valley. The air becomes more humid, then less clear; the sky is no longer blue. We find ourselves in a fog. Where did the well-defined surface of the clouds go? It vanished. Its disappearance is gradual; there is no surface that separates the fog from the sparse air of the heights. Was it an illusion? No, it was a view from afar. Come to think of it, it`s like this with all surfaces. This dense marble table would look like a fog if I were shrunk to a small enough, atomic scale. Everything in the world becomes blurred when seen close up. Where exactly does the mountain end and where do the plains begin? Where does the savannah begin and the desert end? We cut the world into large slices. We think of it in terms of concepts that are meaningful for us, that emerge at a certain scale.