The book itself is a curious artifact, not showy in its technology but complex and extremely efficient: a really neat little device, compact, often very pleasant to look at and handle, that can last decades, even centuries. It doesn't have to be plugged in, activated, or performed by a machine; all it needs is light, a human eye, and a human mind. It is not one of a kind, and it is not ephemeral. It lasts. It is reliable. If a book told you something when you were fifteen, it will tell it to you again when you're fifty, though you may understand it so differently that it seems you're reading a whole new book.