In 1938, a 23-year-old kid named Orson Welles and his Mercury Theater company broadcast a radio play based on H.G. Wells' 19th century science fiction novel, War of the Worlds, on national radio. It started at 8:00 pm on Sunday, October 30, with an announcement that the Columbia Broadcasting System and its affiliated stations would be airing the production based on the familiar book.

This was the golden age of radio, and millions of Americans were gathered around their radios that evening, listening. Unfortunately, most of them were listening to the end of a comedy sketch on NBC, featuring Edgar Bergen and Charlie McCarthy, and they only switched over to CBS after the ventriloquist bit was over.

That was at about 12 minutes past the hour, well past the introduction. The fictional Martian invasion was already well under way, and the actors were very convincing, and the sound effects were superb. Also, the fact that it was presented as if it were a live, breaking news event helped contribute to what became one of the largest, unwarranted nationwide panics this country has ever seen.

Hundreds of thousands of Americans were convinced that Martians had, in fact, landed in Grovers Mills, New Jersey, and were now at war with humanity, and countless residents of New Jersey even tried to flee the state, jamming highways in their frenzied exodus from the extraterrestrial invasion.

It was just a radio play, but the overwhelming, visceral reaction helped propel young Welles to superstardom in Hollywood as he was given carte blanche to create his magnum opus, Citizen Kane, in 1941.

This was one of the earliest indications of the power that electronic mass media wields and its ability to mold our collective consciousness, for better or for worse. Fast forward 37 years.

It was the summer of 1975, and a 28-year-old kid named Steven Spielberg and Universal Studios made a feature film based on Peter Benchley's novel, Jaws. It was released in theaters on Friday, June 20, and audiences were soon lined up around the block to see the most talked-about film of the summer.

It is estimated that the budget to produce Jaws was $8 million, but it nearly recouped all of that in the opening weekend alone. More than 67 million Americans went to see it that summer, and it was the first film to gross over $100 million. Thus was born the summer blockbuster.

But despite the fact that everyone knew this was a fictional film with a mechanical star, the public responded as if they'd just watched a horrifying documentary about an actual, giant shark that was eating people just for the fun of it, and folks stayed away from beaches by the bus load. Nobody wanted to get back in the water.

Now, on the fortieth anniversary of its original, theatrical release, Jaws is scaring people all over again. Movie theaters across the country are staging special screenings of the four-decade-old-film, many of them at an eerily coincidental time when a number of rare, bizarre shark attacks were taking place on the east coast.

I lined up at the vintage theater downtown to catch Jaws as part of their summer classic film lineup, and sat with 800 or so other folks to watch a movie I'd seen many times, but never on the big screen.

My observations and informal polling led me to conclude that most of the audience had never seen it on the big screen, and a fair number of them had never seen it at all. This included, to my secret delight, the teenaged girl seated next to me with her family.

I was impressed (but not surprised) by how exciting and tense the drama was as it unfolded, super-sized, on the silver screen in front of me, exponentially bigger than any television viewing I'd ever experienced. But watching the girl next to me scream and bury her face in her mother's shoulder was worth the price of admission.

She jumped out of her seat more than one time, and even smacked me once, accidentally, when she recoiled at a particular scene. The group behind me included one person who had seen it and three who had not, and the veteran viewer was instructing the newbies when to shut their eyes. Audible gasps and screams were heard many times, rippling through the theater, and at least one box of popcorn inexplicably leapt from someone's hands into the hair and laps of the people in front of them.

It gave me a glimpse and a sense of the sort of national panic that, 40 years ago, inspired millions of people to avoid their beloved beaches for fear of being eaten by a make-believe shark. Intelligent, rational people who, two hours after a Friday night date, were canceling vacation plans en masse.

Meanwhile, a young director was rocketed to superstar status, going on to direct such hits as Close Encounters of the Third Kind, Raiders of the Lost Ark, E.T., the Extra-Terrestrial, Jurassic Park, Saving Private Ryan, and, in a weird tie-in to the Orson Welles story at the beginning, War of the Worlds.

The movie itself is about the fear that grips a small, New England island community when, over the Fourth of July holiday, a gigantic great white shark begins to terrorize residents and visitors. The new-in-town police chief (with a fear of the water) becomes the center of the crisis, and he joins forces with a cocky, young marine biologist and a grizzled, slightly unbalanced, old fisherman to track the beast down before it can wreak more havoc.

It is a story that unfolds with patiently suspenseful pacing, with much of the fear and anxiety created by the fact that we almost never see the monster until closer to the end of the movie. We may see a fin, we may see something disappear from the surface of the water, and we certainly hear the ominous notes of the tuba, which composer John Williams described as, "grinding away at you, just as a shark would do, instinctual, relentless, unstoppable."

I'd like to say that much of this suspenseful buildup was the genius of young Spielberg, but the reality is much simpler: the mechanical shark, nicknamed Bruce (after Spielberg's lawyer), almost never worked when they put it in the ocean.

As a result, most of the director's plans for big, scary, shark-filled action scenes were scaled back significantly out of necessity, and the work-around was to shoot a great deal of the movie from the shark's perspective, at shark-eye-level, half-out of the water. The result was brilliant: a terrifyingly voyeuristic perspective, as we see the approaching doom as if strapped to the shark's back.

It may surprise you to learn that it is not a terribly gory film with gratuitous scenes of blood and guts. It is, however, a film that will elevate your heart rate and make you think twice about what's in the water, just out of sight.

There are some brilliant performances from Roy Scheider as Chief Brody, a young Richard Dreyfuss as the marine biologist Hooper, and Robert Shaw as the somewhat deranged captain of the Orca, Captain Quint.

In one powerful scene, as the three would-be shark hunters are sitting in the cabin of Quint's damaged boat, Quint recalls his experience years earlier as a young sailor on the doomed war ship Indianapolis, which was sunk in shark infested waters in the latter days of World War II. It is both gripping and haunting, and the perfect prelude to the final showdown with the giant shark.

One of the most famous lines of the movie was never scripted, and provides some uncomfortable comic relief as our heroes are battling the giant great white in the open ocean. Roy Sheider, as the shark reveals itself fully for the first time and nearly capsizes the fishing vessel, ad-libbed, "You're gonna need a bigger boat."

The movie explores not only the mass hysteria that mob mentality can so easily create, but also the irrational behavior that a desire for profit spawns. Shutting down a resort town at the height of summer vacation because of a monster shark attack might seem like an easy conclusion to come to, unless you're the mayor of said town and all the people who voted for you are counting on making most of their annual income off of the tourist traffic.

It's all a fascinating look at man-versus-nature and man-versus-man and man-versus-self, wound up in a powerful visual presentation with one of the most memorable soundtracks ever written for a motion picture.

It is worth noting, however, that author Peter Benchley stated in later years that had he known about the actual behavior of sharks when he wrote the book, he never would have written it at all. Tragically, the same irrational fears that kept some people out of the water also led other people into the water to hunt sharks at an unprecedented rate, threatening the survival of some species.

Benchley became a staunch shark conservationist for the rest of his life, but the primal fear created by his oversized story continues to terrorize beaches and movie theaters everywhere.

Bottom line: 40 years later, Jaws is still worth watching. Not for little kids, unless you never want them to enjoy a beach vacation (or possibly a bath) for the rest of their lives, but it is a pretty good ride.

Everyone knows, before they ever sit down to watch it, that this is a movie about a giant shark. But what everyone learns is that waiting for the shark to make his screen debut is far more frightening than actually seeing him. And director Spielberg learned, accidentally, what director Alfred Hitchcock always understood: "There is no terror in the bang, only in the anticipation of it."