Balance matters. Even in photos. It is as if the subjects (those that are not part of the background) in a photo weighed proportionally to their apparent sizes. When we look at a photo, we hold it up in our mind and hang from the middle of the upper edge to see if the picture would tilt to either side, depending on the 'weights' of the subjects in it. Our intuition as regards things placed on a see-saw, further dictates that the further a subject is from the centre of the frame, the heavier it affects on the frame. If different-sized subjects are placed at appropriate spots, it is possible that the picture would not tilt to either side. By then, we would find ourselves looking at a well-balanced photo.
