Finally, a thread that tackles one of the most important things! All academic theories of photographic composition come directly, with a few elaborations, from theories of painterly composition. Forget about photography when learning about composition, it is a very recently invented tool. Go to the painters and draughtsmen who have been working since man first began to walk upright. For an understanding of picture-making in general it is wise to start with the greatest -- da Vinci's treatise on painting, unfortunately scattered through his writings and cluttered with his inimitable asides, but giving a unique understanding of seeing and perceiving from the hand of the greatest draughtsman who ever lived. Many of his insights cannot be understood until you have achieved a certain "serenity of seeing" that is very much at odds with modern life. One always falls well short when one deals with da Vinci.
Study the paintings of the Masters in all their glory, absorb their theories when they expressed them (they often did), there is nothing that a reasonably well-educated person cannot understand. Art history is largely irrelevant in this pursuit, since it deals primarily with tracking content -- inspiration and influences from the historical perspective -- with very little to say about how pictures were made, the materials and techniques involved.
Above all, become at least an adequate draughtsman as someone has already expressed. Forget photography. Spend a year in a life drawing class with a good teacher and pleasant fellow students. Expose yourself to the human figure and a large, empty sheet of paper. Start seeing in earnest. It is no coincidence that many of the greatest photographers knew how to draw rather well.