On the other hand, I routinely have to take a box of books to Goodwill, the library sale, or the dump. I can still refer to every digital work I've ever owned,

On the other hand, I routinely have to take a box of books to Goodwill, the library sale, or the dump. I can still refer to every digital work I've ever owned, whether on Amazon or pdf. So which is really a more secure way of containing knowledge?