Even before box office receipts from this weekend's opening of Harry Potter and the Deathly Hallows, Part 1 are counted, the Harry Potter story is already the most profitable international movie franchise and the most successful book series in history, in terms of volumes sold. What has driven a children's tale about a young wizard and his friends to such heights? Here are five theories:

1. We're suckers for a good orphan story

"We root for Harry Potter for the same reasons we root for Oliver Twist and Shirley Temple," says Steve Daly in Newsweek: They're orphans. Author J.K. Rowling goes one further and makes Potter an "amped-up orphan hero" dramatically "wrenched" from his parents and forced to save his world from the evil "megalomaniacal wizard" who killed them. But the appeal's the same: The "essential comfort food" of a boy or girl "alone in the world... finding a way to help themselves while we eat popcorn."

2. The characters are adolescents

"What Rowling has done... better than any popular author," says Alyssa Rosenberg in The Atlantic, is give us compelling, vivid characters in their dramatic prime: Age 11-17. "They burn so brightly" because of the "preciousness and specificity" of those teenage years — nobody wants to see Harry grow old any more than we wanted to witness the decline of Michael Jackson, "the last boy to be as famous and as enduring." And unlike Twilight's cardboard heroine, Hermione Granger is perhaps the "most progressive popular romantic heroine of a generation."

3. There's something magical about... magic

"The appeal is obvious," says Sarah Bryan Miller in the St. Louis Post-Dispatch. Rowling's created world is full of wizards and magic. Who hasn't wanted "to simply wave a wand, recite a spell, and effect a magical change on some person, object, or situation?" So real does her creation seem that my kids hoped against hope that a Hogwarts "owl would be arriving with a message for them," says Rick VanderKnyff in The Boston Globe. What's more, they prefer their imagined takes on the books to the movie versions — "now that's magic."

4. Everybody loves a rebel

Harry Potter is "a kid who appeals to people all over the world" because "he dares to defy authority," says Sarah Cantrell, a University of North Carolina PhD candidate whose dissertation focused on the Potter phenomenon, to The Daily Tar Heel. "That kind of rebellion gives children lots of hope," especially, because they "don't have a voice in Congress, can't vote, and can't drive. There are lots of rules and regulations that govern them." Harry, on the other hand, "acts in spite of and because of the circumstances presented to him."

5. The story taps into religion and mythology

According to Macy Halford in The New Yorker, "No book in recent times has been as maligned" but also "defended as vigorously" by the same religious group: Christians. Like C.S. Lewis' classic Narnia series, the Potter saga — which has been called the "most powerful contemporary retelling of the gospel narrative" — resonates with the faithful, but not at the expense of storytelling craft. Its appeal is broader that that, says Kathy Nance at St. Louis Today. Rowling "drew from an archetypal well that... goes beyond religion into the core of our psyches and spiritualities," using myths and legends to appeal to Christians and pagans alike.