It is not widely understood that the most meaningful photographs often work through the power of metaphor. Let me take an example - a photograph of mine of shoes in the hall called 'Home'.
From the moment I saw this scene in the hall at home, and before I took the actual picture, I knew that it was a powerful metaphor. And, like many metaphors in art, it works on different levels - and works differently for different individuals
For me this image, with its intensely warm, early palette, conjures up feelings of home and snugginess. The shoes have been left at the front door, so the person is inside with you. The distance from the shoes down the hall to the lower edge of the photograph is a welcoming journey into the house - and into a house where you are not alone; you're with someone you love.
But like all good metaphors, you will have your own reactions to it - hopefully equally positive, but your own.
Of course, many metaphors are not a warm or as joyful - the picture 'Alone - San Francisco' is an interesting example. It's clearly a strong image with a brutal concrete background. I deliberately composed the image with him as a small part of the frame. This just accentuates his isolation - or with his direct stare into the camera his strength and perseverance against adversity. Or is it both.
The point is that the image resonates with the viewer because of the difficult metaphor it uses.