If you are familiar with Harry Potter, you will know about the Mirror of Erised. Harry stumbles across this remarkable object, tucked away in a disused classroom, during his first year at Hogwarts School of Witchcraft and Wizardry. The magical mirror doesn't show a person their reflection, but instead it gives a depiction of their heart's desire. There is an inscription across the top which states this - backwards, of course. "Erised stra ehru oyt ube cafru oyt on wohsi."
When Harry looks into the mirror, to his surprise he sees himself with his parents, who had actually died when he was just a baby. Captivated by this image, he tries to show it to his friend, Ron, but Ron doesn't see the same thing at all. As Professor Dumbledore puts it when he finds Harry there: "It [the mirror] shows us nothing more or less than the deepest, most desperate desire of our hearts". Harry spends a lot of time in front of the mirror, looking at alternative reality that can never be, and using it as the next best thing to having his parents actually back with him.
I was reminded of this the other day, as I was sorting through some stuff on the computer and looking at some old photographs. There were a couple of pictures of Debbie from before she was ill - one from a several years ago - which triggered all sorts of memories. After a while, I realised that I had been daydreaming for a little while in front of one of the pictures on my computer screen. My imagination had taken me back to the scene where the photo was taken, and just for a moment I was enjoying the happy moment the photo captured, as if I was there.
Reality returned with a jolt, with the realisation that I was sitting in my study on my own, and whilst it was a happy memory, I couldn't actually go back there. So I understand the draw for Harry to the mirror. In his case, it was to dwell in a scene which could never be - sharing time with his parents as an older child. For me, it would be to travel back into the past to be with Debbie, fit and well.
But tempting though this is, it is also potentially destructive. You can't stay there in front of the mirror for ever, as it disconnects you from reality. Dumbledore says to Harry that "men have wasted away before it [the Mirror], entranced by what they have seen, or been driven mad, not knowing if what it shows is real or even possible." Looking through old pictures with friends and family is fine from time to time, to tell stories and remember, but as Dumbledore concludes "It does not do to dwell on dreams and forget to live. Remember that."