I saw this great quote in a touching memory from Scott Evans on his grandfather dying:
When my father died, it was like a whole library had burned down. -Laurie Anderson
One of the stories I remember from The Tipping Point was about how when you're with someone for a long time they become an external repository of memory for you. So all you need to do is store a pointer to that memory rather than the memory itself. That's one of the many reasons people are so screwed up when a mate dies, part of what they know and remember has been suddenly ripped away and isn't coming back.
My mom was like that for our family. My dad knows bits and pieces, but because he was on cruise for big swaths of time there are events he just wasn't there for. And many of the memories I knew were with her but because there wasn't a good reason to draw them out (like a grandkid), I didn't.
This is coming up more frequently now with the baby because one of the questions you always wonder is, "What did I do?" Like: when did I start to walk? Or read? How long was my teething? All that stuff that was once boring but that apparently becomes everything when you have your own. Another of those life stage events that highlights the loss.