Harry Potter: Only four keys to success?

Over the past few days, I've been researching the marketing strategies behind Harry Potter. One article published on Business Week suggests that those strategies are fourfold:

1) Narrative. J.K. Rowling makes sales because she writes well.

2) Ambiguity. Harry Potter appeals to a wide audience, attracting children and adults alike. In addition, Rowling blends different literary genres; not only is Harry Potter a fantasy novel, but it's also a bildungsroman and a thriller.

3) Mystery. Rowling bases much of her plots on secrets, making sure her readers keep the pages turning. (Consider also The DaVinci Code, which likewise captivated readers with secrets, mysteries, and forbidden knowledge galore.)

4) Entertainment. People read Harry Potter because it's fun!

That's Business Week's take on the phenomenon. Personally, however, I think there's more behind Harry Potter's success than these four strategies alone - narrative, ambiguity, mystery, and entertainment. Stay tuned.