Photographs are, in many ways, anchors launched from the unstoppable stream of time, an attempt to redeem images from their inevitable disappearance. Why do we focus on image? Why has not become common the use of sound recorders leading people to walk around, recording the sounds of events for eternity?
First of all, because we would have to listen to them in real time. Images allow us to imagine movement from still, and we can look at several at the same time. We have learned to put sounds and smells on each of them and the photographers learn how to suggest the ways. This is an important part of our apprenticeship as visual interpreters.
The same way as we learn to decode, organize and select the multiplicity of senseless light reflections received by our two dimensional eye, so the photograph can present its own magic gimmick to make us see through it and beyond our time grids.