Timelessness is nice, as far as it goes (although it's an awfully hard assertion to prove before any actual time has passed). But as a compliment, it fails to give Rowling her due for something just as tricky: timeliness. The most enduring works of fantasy fiction have always begun by being firmly rooted in their own moment, not by shooting for immortality. A century ago, when L. Frank Baum was writing his books about Dorothy Gale and the land of Oz, the contrast between a windblown, uneventful, monochromatic world of middle American farmland and the exoticism and magic and horror and danger of cities that seemed impossibly far away didn't require a leap of imagination for his readers; they were living it. J.R.R. Tolkien's Lord of the Rings and C.S. Lewis' Chronicles of Narnia were both forged in the fire of World War II; the notion that the fate of the world was at stake in an epic battle between good and evil, and the explicit connection between wickedness and a deranging lust for power, was as alive in the newspapers as it was in the stories they told. And George Lucas' first Star Wars trilogy dovetailed so neatly with the rhetoric that marked the final years of the Cold War that politicians of every stripe continue to appropriate it. Not only has Hillary Clinton referred to Dick Cheney as Darth Vader, but President Bush has suggested that the vice president doesn't even require a costume for the impersonation.

To see how apt a product of our era the Harry Potter books are, you have to take the series apart a little before putting it back together. Now that the long-awaited last words (''All was well'') are official, Harry's saga seems like one 7-volume novel (especially since it's been repackaged in a mammoth faux-Hogwarts-trunk cardboard box; look for a sudden spike in parental lower-back injuries around Christmastime). But the Potter books really read as two distinct trilogies — the first one episodic, light-spirited, and aimed largely at children, and the second, much longer and darker one designed for a general fantasy audience that includes both adults and kids and demands a more sustained attention span and a willingness to grapple with the kind of horror that can't be wanded away by spells and charms. Book 4, Harry Potter and the Goblet of Fire, is the sinew that connects the first trio of books to the second; it's the one that starts with a long, larky trip to the Quidditch World Cup that turns nightmarish, and concludes with a chapter tellingly entitled ''The Beginning,'' a road sign letting readers know that they are about to be taken into a tougher, grimmer, more frightening place.

The first four Harry Potter volumes arrived in U.S. bookstores at a breakneck pace between September 1998 and July 2000. And then, after ''The Beginning,'' came a wait that tested legions of faithful readers: three years. Rowling keeps most details of her plotting process in her own chamber of secrets, unveiling the occasional tantalizing nugget about her decision-making on her website or during an interview or public appearance, but rarely getting specific. Like any terrific storyteller, she knows the value of leaving certain things untold. So unless she decides to spill the many-flavored beans herself, all we can do is guess what happened. Three years bisected by 9/11; three years during which Rowling remarried and had an actual, nonfictional son of her own; three years spent toiling on an installment of her saga so long that she admitted it drained her energy.

NEXT PAGE: Rowling's effect on a generation's ideas about war, leadership, dissent, heroism, and sacrifice