From the article:
"Imagine if you were given a book for Christmas. You could read it as much as you like, but could only store it in a maximum of three shelves before it burst into flame and exploded in a firey ball of destruction. Now you could just leave that book on the same shelf and move everything else around to make sure you didn't have to remove it. But eventually, there's going to be a fire, or some other error, or you'll want to move, or upgrade shelves. You might want to share the book with a friend, let him or her borrow it for a while and put it on their own shelf. You might even want to sell it to get some money for new books. Books are traded everywhere. They're even available at the library for free. And yet, the book industry isn't collapsing, it's doing quite well. It always has. The used-book industry has enormous numbers, but no special chips are being installed in books to make sure they aren't re-sold. And you can put them in as many shelves as you want. It's illegal, but nothing can stop you from photocopying the whole thing. Until Sony's new reader begins to replace physical books, book trading will be easy and more or less free."