The other day I was talking to an old Hollywood hand who was astounded by the runaway success of "Inception." It turned out that he'd seen the film on its opening weekend in a private screening room with a number of industry elder statesmen, including at least two former studio chiefs and a couple of their young offspring. After the movie was over, the industry elders were shaking their heads in disbelief, appalled by the film's lack of clarity, having been absolutely unable to follow the film's often convoluted story.

But before anyone could register their complaints, one of the younger people on hand, flush with excitement, praised the film to the rooftops. To him, it was such a thrill ride that if the projectionist could show the film again, he'd sit through it again right away.

Clearly "Inception" has struck a deep nerve with moviegoers. The Leonardo DiCaprio-starring film has been the No. 1 movie in America for three weeks in a row, having racked up nearly $200 million in total domestic box-office grosses, easily making it the biggest surprise hit of the summer. But from the moment "Inception" was released, it was obvious from polling data that the movie had created both a critical and a generational divide. Some critics have raved about the film's originality while others have mocked its excesses. If you were a young moviegoer, you loved the visually arresting puzzle-box thriller. But the older you got, according to polling data, the more likely you were to detest its run 'n' gun, dream-within-a-dream complexity.

I guess I'm somewhere in the middle ground of the debate, since I was dazzled by the movie's originality, but also so confused by its dense, video-game narrative style that by the last 40 minutes of the film, I'd pretty much lost track of the story. You might say I'd been forced to suspend both belief and disbelief.

But what makes "Inception" so fascinating is that it joins a host of groundbreaking movies that have inspired either a generational or critical divide. The contentious reaction to "Inception" has a lot in common with the response to such equally daring films as "Breathless," "Bonnie and Clyde," "The Wild Bunch," "A Clockwork Orange," "Taxi Driver," "Reservoir Dogs," "Pulp Fiction" and "Natural Born Killers," to name but a few. People either love 'em or hate 'em, with young moviegoers usually being the first to wrap them in a firm embrace.

I'm not here to say that it's time to put "Inception" into the pantheon of great films, since some of the films on that previous list probably don't belong there either. But they all grabbed us by the collar and didn't let us go. "Bonnie and Clyde" offers perhaps the most classic example of a generational breakthrough film. It was initially panned by a host of critics, most notably the New York Times' influential Bosley Crowther, who called the picture a "cheap piece of bald-faced slapstick comedy,"

Time and Newsweek, then important arbiters of taste, panned it too. But something crazy happened. Young moviegoers swooned over it, starting to talk and dress like the characters in the film. Joe Morgenstern, then the Newsweek film critic, famously went back to see the movie a second time with an audience--and came around, recanting his first review with a more enthusiastic one. Before long, Time had put the movie on its cover as a symbol of the new youth culture in action and the Times had put Crowther out to pasture, hiring a younger critic in his place.

There were similar divisions with other films over the years. Many critics gave "Clockwork Orange" the cold shoulder early on. Audiences were often initially repelled by the violence in "The Wild Bunch." The merits and demerits of "Taxi Driver" were ferociously debated before it settled into its middle age as one of the most admired films in Martin Scorsese's oeuvre.

Quentin Tarantino's early movies inspired much wrangling as well. Stacy Sher, who produced "Pulp Fiction," remembers that audiences early on were bitterly divided. "The perfect example was a test screening that we had in Seattle," she recalls. "One-third of the audience loved it, one-third hated it and one-third walked out." The film eventually became a huge hit, but only after it won the Palme d'Or in Cannes and got a host of thumbs ups from various critics.

In the old days, the culture zeitgeist took much longer to coalesce. Now buzz is often instantaneous. "Inception's" opening weekend was made up of young male zealots and Chris Nolan acolytes. By the time I saw it again last weekend at a local mall, the audience was full of a much broader cross section of moviegoers who simply wanted to find out what the excitement was all about.

In today's media-saturated culture, a film that polarizes its audience is often a film on its way to hitdom. When people argue vociferously about a new movie, the talk alone is the best possible promotion. If you haven't seen the movie, you're on the outside, wanting to get in on the action. When you hear people who care enough about a film to argue about it, you want to see if for yourself so you can decide whether you're a hater or a lover. In a sense, the film creates its own word of mouth.

If "Inception" plays especially strongly with a young audience, it's probably because they instinctively grasp its narrative density best, having grown up playing video games. "When it comes to understanding 'Inception,' you've got a real advantage if you're a gamer," says Henry Jenkins, who's a professor of communications, journalism and cinematic arts at USC. " 'Inception' is first and foremost a movie about worlds and levels, which is very much the way video games are structured. Games create a sense that we're a part of the action. Stories aren't just told to us. We experience them."

Even though the density of "Inception" can be off-putting to older moviegoers, it's a delicious challenge for gamers. "With 'Inception,' if you blink or if your mind wanders, you miss it," says Jenkins. "You're not sitting passively and sucking it all in. You have to experience it like a puzzle box. It's designed for us to talk about, to share clues and discuss online, instead of having everything explained to us. Part of the pleasure of the movie is figuring out things that don't come easily, which is definitely part of the video game culture."

You could argue that the art-house cinema of the 1960s, especially the great works by Bergman, Godard and Antonioni, inspired the same kind of pleasures for moviegoers eager to tease out the meanings from their films' arresting (and often impenetrable) images and symbols. But Jenkins argues that because of today's huge online social networks, there is a far bigger audience available to engage in debate over a film like "Inception" than ever existed in the '60s.

It doesn't mean everyone is going to adore "Inception." Nor does it guarantee that the film will stand the test of time. But like all of the other movies that inspired ferocious critical tussles in the past, "Inception" represents something we rarely get in today's corporate Hollywood. It's a personal film by a director with a distinctive voice. Put simply: It's a movie that matters.

Photo: Leonardo DiCaprio waving to fans at the premiere of "Inception" in Tokyo last month. Credit: Franck Robichon / European Pressphoto Agency