This was an interesting history, it seems like we actually kind of don't really get a clear answer or at least a clear villain. A lot of the discussion pieces from before 1950 seem to be talking as if the rule of thirds is widespread as informal advice, just that nobody is writing it down. And then the military manuals come in and they have to write all of this stuff down so they do?<p>I had a really great photography class in high school, complete with a dark room and developing our own negatives. When our teacher talked about the rule of thirds he phrased it in a very interesting fluid way, I only learned later that some people hear it as a much more rigid “this is how you have to compose” way.<p>He said, if you have multiple subjects in the painting, there are kind of natural lines between them, and because your eye moves from one to another, there is natural movement along those lines while the subjects themselves get kind of “anchored.” So like if you want to sell “busy street” you capture a beautiful house on the left and right, say, so that the eye is constantly moving along the busy street.<p>And then he said that if you only have one main subject, you have to decide whether you want it to be in motion or at rest. If you want it to seem still and fixed and kind of eternal, you put it at the center. Dead center is a place of balance, our eye is naturally drawn to it, if you put the subject in the center there will be no motion.<p>And only after all of that, he draws the rectangles and divides them into thirds both ways. And then continues, by putting something off center, on one of these lines, it gets a sense of motion towards the other 2/3rds of the photo since the background is expanding out in that direction. And especially at these four corners, there is a very strong diagonal motion towards the opposite corner. “So if I want to take a photo of someone walking into the great unknown, I place them at the bottom right corner and try to get the path snaking up this way, you get a real sense of movement then.”<p>Today I think that that makes it a little bit too scientific, I think things can look in motion in the center and static in the corners, so I think of it as just kind of a trick of the eye, I think it can be effective but I don't think it has to be that way. But it still made a good lasting impression on me.