So, we have found that certain types of lines, as lines make up shapes, do different things to the way we see it and feel about it. if we were to observe that there are other shapes, like squares, spheres and triangles, then we could maybe see the work as a 'collage of shapes' too? These more vague and subtle shapes will also influence the way you feel when you look at the picture for 'your own ends.'
If we were to look at squares, well, there are already squares around the outline of the picture usually. this is to be neat and tidy most of the time, but as i said previously, the squares make your subconscious go around the whole outside to separate the picture from what else you see, like the wall it is mounted on. i suppose we might find squares boring, seeing them all day in the way of walls and doors and other things, this is why cars with curves are so sought after, of course. if you were to observe that squares of different styles make for good maths drawings, then it must be logical to say that squares are easy to understand, therefore flow over your periphery or image of the art work quickly, allowing for a second look, and a third. this means that we find square shapes soothing to us, as they decipher so easily.
Then there are spheres, typically someone's face or body. these are good for likening our complicated features to the picture, but, if one was to think about it, we would feel as if we were looking in a mirror! this means that the 'face' or 'sphere' needs to be dented correctly, as, if has definition on it, and it does not allow for a quick analysis of the picture, then it will make us uncomfortable with the sphere, likening it to our face, and think our face is hard to take in. this will make us feel ugly and there is no ways we can enjoy a picture like that.
Triangles are like noses and often hands. there are other triangles too, but they are used seldom. i figure the triangles will make you feel like you are looking at a roof of a house, so naturally the best place to put them is above the focus of the image, yes? if you were to put a triangle above a cross, then you will compliment both of them, as, you will first look for the triangle, as you want to see what is at the top of the picture, and then easily decipher the cross, going back to the triangle and then the cross - evidently this is the way most people would approach it. people look to the top of the picture often when they consider it at all, wanting to see what all the fuss is about.
These theories could be tested on other established arts, but let me draw a comparison to the often used mona lisa? this is a simple face with the right denting to the sphere, triangles at the bottom of the picture with her hands and her head also resembles a triangle, as her hair sits like that. this would be so appreciated because the outline of the triangles is taken in nearly as quickly as a square or line, and they frame the sphere of the face so nicely.