It’s a way to transcend time and to be connected to people in your family you feel you might not easily relate to because of the generational divide, especially if they’ve passed. It’s a look into their genuine interests and personality, especially if they’ve annotated in the margins. The ability to do this is valuable if you can. I think it builds or strengthens empathy, and gives you a stronger foundation for appreciating your family history. Not to mention you’ll likely get an interesting reading experience out of it. The (+) is for great-grandparents and beyond.