You know, physically. Logically, I know that when I cut myself it hurts, but my memories and dreams of the cut do not. Although some memories create a specific response - grief or happiness, the memory itself doesn't. For example, as the weeks and months pass, we no longer feel the overwhelming joy of a wedding day. We question ourselves and may even remember the day differently, our minds filling in gaps that create a plausible story line.
Time passes and memories fad, its inevitable. Sometimes all we have is a relative memory of a specific instance in time; the absolute long gone. Looking at a photograph sparks the memory, that leads to the absolute, "the event". Once filed under things to remember, the photograph makes it real, the photograph takes us back in time to places we have long forgotten. The relevance of photography is simple, - accept change, but remember the absolute.
I have my own favorite images; ones of my children when they were young, ones of my wedding day. Pictures are indeed worth a thousand words, but in reality they are priceless. No value can be placed on these images we hold close to our heart. They are our way of reliving and remembering our lives, our events, our absolute.