A trip down memory lane

Last week when I was babysitting I found some books in the child's bookshelf that I remembered from my childhood.
They were actually a collection of 4 books from 1965 that each contained a collection of Disney stories. Each book had a different theme. There was America and Fantasyland and I didn't really look at the two others.
I know that when I was growing up my babysitter had these books and I remembered them but after looking at them I couldn't remember why I thought they were so great.
I opened the America collection where I found stories like Pollyanna and Old Yeller.
As I was flipping looking at the book I commented that I didn't know what Old Yeller was doing in this book since it was a sad story.
Instantly the child's ears perked up and she wanted to hear that story but not actually from the words just from the pictures. So I told the story as best I could from the pictures.
There is a picture close to the end of the story where Old Yeller is barking and snarling at the door. So I explained that Old Yeller got sick and he barked at his people because he was sick and then he died.
The child I was babysitting for could not figure out what was so sad about Old Yeller dying. "What's sad about that?" Again and again she asked what was sad about the dog dying. I tried to explain but I think because her family has an older dog she has already prepared herself for the fact that her dog will one day die.