Fahim, I did not write that diagonal lines don't give a different feel than straight lines or that lines leads to no point. I wrote:
The operative word here is "fixed".
Now, let me let aside religion and people's sanity aside for a moment, I will not dive into that. You are telling us, if my understanding is correct, that there is some truth in leading lines, the different feelings associated to different orientation of the main lines in a pictures, the different weighting of elements in a picture, etc... This is correct.
This is correct, but it does not make a complete theory. A complete theory is a theory which allows one to build an automated process and the output of that automated process are indeed pleasing. This works for music, so the theory of harmony and counterpoint is complete. This also works for colour, so the theory of colour harmonies is complete.
This does not work for composition. People, smarter than me, have tried to teach a computer to make a Mondriaan. They failed.
So it is true that part of the theory work: the ancient Greeks built well-proportioned temples by using the golden ratio. But we still have some work to find out why we like to look at certain things and not at other.
Thanks, Jerome - balance and succinct argument!
So we CAN indeed use some such structural guides to give our photographs some tendencies towards reproducible emotive effects!
That's what I expected. We don't need any "complete theory" in order to leverage current knowledge in our daily photography!