Maybe this has happened to you. You’re sitting in a train looking out the window at an adjacent train on an adjacent track. It’s very close to you. One of the two trains slowly starts to move. Is your train moving backward, or is the other train moving forward? Momentarily you can’t tell. The sensation is perplexing. Your brain assumes the stable visual field is the largest visual field, and determines whether an object is in motion by contrasting the smaller area with the larger area. But now, the area out your window and the area in your immediate space seem to be at parity in terms of how much of your visual field they occupy. The brain checks for other clues like; do I feel motion (a jerking or saddling motion perhaps)? If the area outside your window occupies the larger part of your visual field then, you will feel as though your train is moving backward, not the other train is moving forward. Our brain checks our location and movement using a variety of criteria. When we are riding a bicycle and look at the ground it appears to blur but, looking down, the bike’s frame appears steady. When we are riding in a fast moving car we notice that the roadside closest to the speeding car blurs more than the distant area. The faster the car moves, the area of blur extends yet further from the car. I took this picture from a car moving at about 45 mph:. The daylight was waning. The visual field closest to my car window blurred more than the distant trees or hills. This closer visual field included a pattern of autumn leaves which appear as a pattern of brief fuzzy orangish horizontal stripes while the more distant vertical trees are less blurred. The picture’s union lies in the contrast of the verticals vs. the horizontals, a device of Poussin’s and later Cezanne’s. Suppose I were to reverse the order as a painter could do, and blur a distant horizontal background against a more static vertically oriented foreground. I give you two examples of that reverse order in my painting samples here. or,. Motion is implied even though the order is reversed.