Other people have said far more eloquent things about the literary work of the late Maurice Sendak than I can manage. However, as someone who's enjoyed reading his books and reading slightly dog-eared copies of them to the kids in my family, his death is a call to think about the priceless nature of books themselves.
I enjoy my Kindle for many reasons, but even if every book I own was available for it and I could replace all the actual books with digital copies for free, I wouldn't do it. My century old copies of stories by Poe or Shakespeare plays aren't just collections of text but rather something unique in their own right, an amazing intersection of the human and the technological. I think this is what Sendak was getting with a comment he made about ebooks in a 2011 interview with the UK newspaper The Guardian.
“I hate them. It’s like making believe there’s another kind of sex. There isn’t another kind of sex. There isn’t another kind of book! A book is a book is a book."