Figure it another way: What if the latest "Harry Potter" had actually been a movie opening? Those 3.5 million book-buyers would have conservatively translated into 10.5 million tickets -- presuming each book-buyer brings a parent and a sibling or friend. At an average ticket price of $5, that amounts to $52.5 million -- easily. Again, it's a number that would have challenged any of this summer's so-called box-office hits. No wonder the weekend's lone family-friendly feature, "Disneys The Kid" -- which stars Bruce Willis as a man who literally encounters the child within -- opened to a lackluster $12.7 million. It had the misfortune of facing the "Harry" juggernaut.

"The movie did just about the business we expected it to," insists one Disney insider. Still, it's a reasonable assumption that Harry fans -- having stayed up late Friday to buy the book, and then passed the rest of the weekend buried in its 734 pages -- were in no need of a Disney fix (so much for the shameless use of "Disney" in the film's title).

Nonetheless, "It was an extraordinary weekend," argues Sony Pictures distribution chief Jeff Blake. "Business was up 25 percent over last year." According to Blake, "No one knew 'Scary Movie' would do $43 million. Both 'The Perfect Storm' and 'The Patriot' had strong holds on their second weekend, 'Chicken Run' held on and 'The Kid' has gone on to do $1.8 million on Monday and $1.7 million Tuesday, so I dont think you can count it out yet."

Perhaps, but the Potter phenomenon could still teach Hollywood a thing or two. In a summer when movie sales have been slack -- after a powerful May, thanks to "Gladiator" and "M:i-2," the box-office slumped during June; even after the July Fourth rally, total sales for the season are still off 3 percent from last year's totals -- you dont need a degree from Hogwarts to learn a few lessons:

1) It's the story, stupid. Monday-morning box-office quarterbacks love to blame the marketing: Could "Dinosaur" have amassed more than its disappointing $130 million if it had opened in mid-June (Disney's traditional post-school turf) rather than mid-May? It's arguable. Was Sony foolishly cocksure to open Mel Gibson's "The Patriot," with its musty history-lesson mood, opposite the more escapist "The Perfect Storm"? Given that "Storm" walloped "Patriot," in retrospect, it sure looks like that might have been the case.

But instead of blaming the messengers, look at the goods they're trying to deliver. At a July Fourth barbecue, I spent time with a family whose 11-year-old daughter could talk about nothing but the impending release of Potter -- she'd read each of the first three books three times and chatted about the further adventures of Harry, Ron and Hermione as if they were her idiosyncratic best friends. Had the kids been to see "Dinosaur"? I asked. Sure, their parents said, but the movie's story line seemed so overly familiar, not even the first-rate special effects impressed them. They certainly didn't clamor for a repeat visit. "When you're dealing with a wide release, once it gets up to around $180 million, then everybody has seen it once," observes Tom Sherak, chairman of the 20th Century Fox Film Group. "You need a lot of repeat business to go beyond that." Adds Blake, "So far, there doesn't appear to be a 'Something About Mary' that has an extraordinary hold from week to week." It's that lack of repeat moviegoers that has kept this season's big movies from breaking through into the rarefied atmosphere of a "The Sixth Sense." Maybe, instead of simplifying story lines -- reducing them to lowest common denominators -- Hollywood should beef them up, especially if it would like moviegoers to take a second look.

2) Dont trash the prototype. A sequel should show some respect for the original work on which it's based. You have to give Rowling credit. In each successive Potter book, she reworks the same formula: Harry escapes the dreary Dursley household and heads off to another academic year at Hogwarts where he battles the evil forces unleashed by the shadowy villain Voldemort. Nevertheless, Rowling keeps embroidering, adding more details and surprises. Now look at "M:i-2." The first "Mission: Impossible" film in '96 effectively trashed the TV franchise on which it was based, unmasking team leader Jim Phelps, played by Jon Voight, as a duplicitous traitor. Beyond a fetish for latex, the new "Mission" doesn't even bother with the familiar tropes -- instead of assembling a team of disparate talents, Cruise's Ethan Hunt, who's now a virtual lone wolf, just recruits a couple of buddies. Instead of an impossibly complicated con job, the movie settles for John Woo-style mano-a-mano combat. Sure, "M:i-2," which has earned $203 million to date, has outgrossed the original, which collected $180 million in domestic ticket sales. But, even if it climbs to an eventual $220 million or so to become the summer's biggest hit, it will still fall far short of last summer's second-place finisher, "The Sixth Sense," which scared up $294 million.

Meanwhile, the rest of the season's sequels and remakes have done far worse. "Shaft," which failed to capture the sexual swagger of its 1971 forebear, is headed toward a midrange $70 million haul. And Universal's two attempts at retro programming -- "The Adventures of Rocky and Bullwinkle," which absurdly turned Boris and Natasha into flesh-and-blood antagonists, and "The Flintstones in Viva Rock Vegas," which took the cut-rate prequel route -- are out-and-out flops.

3) Mystery sells. The newest Potter debut is even more astonishing considering that Rowling and her publishers held back the novel's name, as well as any description of its contents, to the very last minute. By creating an aura of secrecy, they added to the frenzy surrounding its arrival.

By comparison, Hollywood -- which spends about $24.5 million per film (and even more in the crowded summer months) hawking its wares -- gives away entire stories with trailers and TV ads that are mini plot summaries. By the time many movies open, you feel youve already seen them. Certainly, "Rocky's" swan dive couldnt have surprised anyone whos suffered through the lame gags in its preview clips. If that was the best the movie had to offer -- pass. And if Warner Bros. could have kept John Travoltas dreadlocked mugging under wraps in "Battlefield Earth," maybe the movie wouldn't have bombed so badly. (Naw, don't think so -- see Lesson No. 1.)

The one movie sell that did emulate some of "Harry's" sleight-of-hand was Warner's "The Perfect Storm." Even though it too was based on a bestseller, its marketing -- focused on that perfect wave upending a tiny boat -- effectively disguised the saga's downbeat ending. The media may have thought it knew the score, but, as one friend who had never read the book confessed to me, he sailed into the film based on the trailer expecting its heroes to survive. "They did a really good job of marketing, emphasizing the excitement of the boat on the water, and the public bought into it just like they bought into 'Twister,'" notes Sherak. "A lot of old-timers thought once the public realized the characters die that it would bother them, but that didn't prove to be true."

But the real test for Warner Brothers comes on Nov. 16, 2001. That's when it has scheduled the release of Chris Columbus' adaptation of "Harry Potter and the Sorcerer's Stone," which has yet to begin filming. The boffo opening of "Harry Potter and the Goblet of Fire" has set a high standard by which the movie's debut will be judged. After all, there's nothing worse than a bad magic trick.