Memories are important.   Like stories and music and just about everything else, they’re important because of the emotional attachment we apply to them. Hey, what’s your favourite song? Have you and your husband or your girlfriend ever heard a tune on the radio and said: “Hey! That’s our song!” before being swept up in a torrent of fond memories and musings and best-forgotten dance moves? Does knowing it’s someone else favourite song or that it ‘belongs’ to a million other couples make it any less unique or special to you?   Nope.   Because the memories conjured by the melodies and the lyrics are yours and yours alone, and that’s what separates it from every other song out there.   Terry Pratchett knew that Death was coming for him. He knew that he was in the grip of Alzheimer’s and he tackled it with the strength, nobility and...