Bookstores across the nation are hyping the June 21 release (12:01 a.m., to be exact) of "Harry Potter and the Order of the Phoenix," the anxiously anticipated fifth installment of J.K. Rowling's seven-book series.

According to the NDP Group, a New York-based research company, half of all Harry Potter readers are over age 35 and a quarter are over 55. Philip Nel, an assistant professor of English at Kansas State University and a widely noted expert on the Harry Potter series, says there are many reasons why the books appeal to different age groups.

"The short answer is that these are good books. Period. All good children's literature appeals to both adults and children because it does not talk down to its readers and because there are multiple levels of meaning," Nel says. Multiple meanings can give a book depth. A person can discover new meaning in the book each time they read it again.

Nel is the author of "J.K. Rowling's Harry Potter Novels: A Reader's Guide." In his book, he explains some of the multiple levels of meaning. For instance, he says the books allude to literary figures like Shakespeare and E. Nesbit, and characters' names have "extra-textual meanings. Minerva McGonagall's first name comes from the Roman goddess of wisdom," he says.

Additionally, the books use strong storytelling.

"As well-plotted mystery novels, these are page-turners," he says. "We want to know what happens next, and that keeps readers of all ages interested." Nel says fantasy appeals to readers as well.

"A young person who discovers his or her powers and grand purpose is a common feature of the fantasy novel and, very likely, a secret wish of many children," Nel said. "As Rowling has said, 'I was aware when I was writing that this was a very common fantasy for children: 'These boring people cannot be my parents. They just can't be. I'm so much more special than that.' She has a point. I suspect it's a secret wish of many adults, too. We may have thought, 'I'm more special than ... this job,' or 'I deserve better than I'm getting.'"

Faithful readers have waited more than two years for the fifth book's release, leading many to wonder if Harry Potter's selling power can match his magical abilities. When asked if the lengthy delay has increased fervor for "The Order of the Phoenix," Nel has one word: "Yes."

But as the books continue to dominate the New York Times' bestseller lists and, a backlash is brewing. Some people view the Harry Potter phenomenon as little more than good marketing wizardry, not good literature.

"Some people tend to conflate the marketing phenomenon with the literature," Nel says. "The larger the marketing phenomenon grows, the more it threatens to obscure the literature. That said, I think that discerning readers will be smart enough not to judge a book by its cover -- that is, to look past the phenomenon and enjoy the book for what it is."

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