There's an old Hollywood story, which may or may not be true, about Humphrey Bogart. He was about to film an "explainer" scene - one of those dialogue-heavy set pieces, where one character drones on for a page or two of crucial, but eye-glazing, exposition.
Explainer scenes are pace-killers, but there's often no other way to let the audience know that the main character is an orphan, say, or how a bomb was defused safely, or that the hero and the mysterious woman had a love affair once, years ago.
But Bogart, like most actors, worried about boring the audience. The story goes that he looks down at the script, with its long column of dialogue, and then tells the director that the only way he'll do the scene, the only way the scene won't bore the audience, is if they place two camels in the background, and hope that they do something interesting.
In the story, of course, he doesn't use the phrase "Do something interesting".
They shot the scene as written, but the director gave Bogart a simple piece of on-screen business. All he had to do to inject some drama was to say some lines while taking out a cigarette, tap it lightly to compact the tobacco, say some more lines, light the cigarette with a match, wave the match out and toss it contemptuously aside, say some more lines, take a big drag, and finish the speech. Cut. Print. Instant drama.
Though his first solution was extreme, Bogart's instincts were correct. In the end, he didn't get his two camels. What he got was a Camel, Unfiltered. And, eventually, esophageal cancer. But it's hard to deny he looked cool.
Smoking in movies has a long, glorious history of effectively solving the Explainer Scene problem. But lately, the movie studios have been bowing to pressure from various cancer organisations to eliminate on-screen smoking. On television, where I work mostly, it's utterly forbidden to have a character take even a small puff. The idea is that if kids stop seeing cool role-model movie stars light up, then they'll stop thinking that smoking is cool.
But smoking isn't cool because people do it in movies. People do it in movies because it's cool. Smoking is a lot more than just puffing away, as Bogart knew. Smoking is a collection of hand movements, lip actions, match striking, and heavy breathing, all at a measured, controlled tempo.
Smoking slows things down - it's almost impossible to light a cigarette quickly - and it's irresistible to actors for the same reason it's irresistible to teenagers: it draws attention to the smoker and away from whatever mediocre dialogue he or she is forced to say, either because of a lazy screenwriter or because of a lack of imagination caused by watching too many music videos.
Smoking is the answer to the question that adolescents and movie stars ask themselves all the time: what can I do with my hands so that I don't look like a boring loser?
With the dialogue in most movies reduced to either one star pretending to be a superhero screaming at the other star pretending to be a different superhero, or one character sitting in front of a computer terminal, and after tapping a few keys, turning to the other characters and saying, "I'm into the system", a little smoke-'em-if-you-got-'em goes a long way.
The ponderous, wooden dialogue of the last three Star Wars movies would have seemed zesty and sharp if only Yoda had dangled a Marlboro from his greenish lips. "Begun," he says, taking a long, slow, last drag, "the clone war has." And then he tosses the butt to the ground and grinds it out with his tiny little green foot.
Bogart's Law is effective in pretty much every sphere of conversation. I often wish that more people smoked, if only to enliven the soul-crushing tedium of most interaction.
Imagine Bogart's Law at the post office: "I'll have a booklet of first class stamps, please." Puff. Blow. Look away. Look back. "Do you have the ones with the kittens on them?" Puff. Blow.
The trouble, of course, is that smoking is a dangerous and deadly habit - not to mention mildly filthy and terrible for your skin. It's a self-destructive and idiotic thing to do in real life - surely we can all find better ways to look cool, right?
But as long as movies and television are rife with explainer scenes and rotten dialogue, it's the best way to keep things interesting on screen.
I suppose we screenwriters could just do a better job at writing, but when a cigarette is so handy, why not just pass one to the movie star and call it a day?
Rob Long is a writer and producer based in Hollywood
On Twitter: @rcbl