You need forensic mathematicians, artists and psychologists as well as scientists. We're learning a little bit about all of it.

The Internet, cable TV, and computer games, account for much more of the trend away from books.

The growth reflects how easy it has become to sell used books and to create inventory in this business.

Now it's time to expand beyond the operational people.

That remains an open question. Some people might argue that it cannibalizes new book sales. Some argue that it spurs new book sales by making more books available and by bringing them to new locations.