Think back for a moment to the kind of desk you had in elementary school - say second or third grade. Mine was square, with a grey metal tub-like bottom and a faux-wood laminate top that lifted up. I often used the top of my head to prop that lid open while I rummaged around inside the general clutter that collected there: folders and looseleaf notebooks and chewed up pencils and erasers and mimeographed work sheets. 

And books.