To apply the category of cause and effect means to find out which parts of nature stand in this relation. Similarly, to apply the gestalt category me… - Kurt Koffka

If an environmental trace is in close connection with the Ego system it will not only be in communication with the particular time structure of that system with which it communicated at the time of its formation; but because of the coherence of the whole temporal Ego system it will be in communication with later strata also.

The second factor, equally important, is that of good continuation and good shape. The things which we see have a better shape, are bounded by better contours, than the holes which we might see but do not. Therefore, when in exceptional circumstances these conditions are reversed, we see the hole and not the things, as the shape of a gap between two projecting rocks with sharp profiles, which may look like a face, an animal, or some other object, while the shape of the rock disappears.

Why We See Things and Not the Holes Between Them. We can now attempt an answer to the question why we do so. Two of the factors of organization which we have so far discussed seem to me to be the most important causes of this effect. In the first place, the segregation and unification which occurs will separate areas of different degrees of internal articulation, and according to our law, the more highly articulated ones will become figures, the rest fusing together to form the ground. Look at any landscape photograph. You see the shape of the things, the mountains, and trees and buildings, but not of the sky.