It would be so easy to explain why J.K. Rowling is 2007's Entertainer of the Year with numbers, not words. The numbers, after all, are so much fun to tally and goggle at: $15 billion (the estimated total revenue generated by the Harry Potter industry); nearly 400 million (the number of Potter books sold worldwide); $4.49 billion (the total worldwide box office gross of the five Harry Potter films, allowing the series to zip past Star Wars and the James Bond films this summer to become the most lucrative movie franchise in history). And let's not forget 1, 2, 3, and 4: the places Rowling holds on the list of the fastest-selling books in the not-very-long history of measuring fast-selling books.

But Rowling never relied on mathematics to gun the motor of the 4,100-page narrative she brought across the finish line this year. So we suspect that she would dismiss the foregoing account as rather dull: Mugglish rather than magical. And although we now know that she is fond of uplifting, even sentimental endings (as long as the joy is qualified by the memory of sorrow and the sentimentality is honestly earned), at this point even she might find her own biography a bit too happily-ever-after; you know, the one that begins in the early 1990s with a young single mother banging away at a manuscript in Scottish cafés, wondering if she could turn her idea into something.

So we'll keep it simple: J.K. Rowling is our Entertainer of the Year because she did something very, very hard, and she did it very, very well, thus pleasing hundreds of millions of children and adults very, very much. In an era of videogame consoles, online multiplayer ''environments,'' and tinier-is-better mobisodes, minisodes, and webisodes, she got people to tote around her big, fat old-fashioned printed-on-paper books as if they were the hottest new entertainment devices on the planet. Let's also credit her for one more thing.

What she spent the last 17 years creating turned out to be completely original. Several years ago, when Rowling's series started to get popular enough to attract attention from the kind of critics who don't usually grapple with popular fiction, she was practically smothered in faint praise that evolved into a low drone of condescension as time went on. Of course, the books are skillful, went the murmurs, but really, isn't this woman merely an adept pickpocket, someone who's synthesized a little bit of Tolkien and a dash of C.S. Lewis and some Lloyd Alexander and a wealth of British-boarding-school stories into a marketable but derivative new package?

No. As it turns out, the Harry Potter books are much richer than their progression from lightness to darkness, from childhood to adulthood, from the episodic simplicity of chapter-books to the heft and sweep of epic novels, and in their constant, book-by-book recalibration of what their readers were prepared to absorb, they've proven unlike anything else in a century of children's literature. Can there be any remaining doubt that Rowling meant every word when she said, some time back, that she planned every aspect of her story ''so carefully I sometimes feel as though my brain is going to explode''? The planning clearly paid off, not only in the blossoming of the books into a worldwide cross-cultural phenomenon but in the widespread declarations that greeted the July publication of volume 7, Harry Potter and the Deathly Hallows, that Rowling had created something timeless, a tale that children would read 25 and 50 years from now.

NEXT PAGE: Why Rowling's achievement isn't just the timelessness of her work — it's also her timeliness