If God could do the tricks we do, he’d be a happy man.
   —Eli Cross, a megalomaniacal movie director in The Stunt Man
 
Film is a visual medium. That’s the first thing you need to know about writing a movie. In prose, it’s all about the words. In film, the image dominates. When you think of a movie, you see an image in your mind.  
 
A woman swimming by moonlight jerked underwater by an unseen force.  (Jaws) 
 
A bumbling detective covering his privates with a guitar as he investigates a nudist colony. (A Shot in the Dark)
 
A lounge singer in a slit dress slithering across a grand piano. (The Fabulous Baker Boys)
 
A girl with fire-colored hair racing through streets to save her boyfriend’s life. (Run Lola Run)
 
A twister spinning a house high above the Kansas plains. (The Wizard of Oz)
 
A Greek hero slashing his sword at the many heads of a ferociously writhing hydra.  (Jason and the Argonauts)
 
A grownup son and his father playing catch on a celestially-lit baseball field.  (Field of Dreams)
 
Go ahead, think of a favorite movie, right now.  What happens?
 
These images can print themselves deeply on our psyches. A personal example. On a Saturday afternoon, when I was around five-years-old, I gathered around the TV with some older kids to watch a horror movie, The Tingler. (Bad idea.) I only remember one thing about that movie, an image, but it’s an image I will never shake. There was this lady, a deaf-mute, and she was lying in bed and then this evil person entered the room with the intention of harming her in some devious way. Terror overtook the lady’s face and she tried to scream but because of her condition as a deaf-mute she couldn’t get the scream out. Now, nobody considers The Tingler a great horror movie and I might find the whole thing laughable if I watched it today but let me tell you that image chilled me in the deepest place.  In my mind’s eye, I couldn’t stop seeing that woman trying to scream! The image gave me nightmares for the better part of a year.
 
Reading prose fiction is largely an internal experience; we slip into the minds of the characters and assimilate our own pictures from the words. In film the reverse is true. We experience a movie from the outside in. We ride along with the visuals and they lead us toward our inner thoughts and sensations and emotions.
 
There is a famous writer’s maxim: show, don’t tell.  This applies double—make that triple—to screenwriting. Watch a good movie. Turn off the sound. You can probably follow the general flow of the story perfectly well, even if it’s a movie you’ve never seen before. If you want to go a step further in your visual education, watch a silent movie. Audiences were held spellbound by movies for several decades when they were completely silent. You’ll find no scarier moment in film than the unmasking of the phantom’s grotesque face in Phantom of the Opera. No moment more heart-rending than the teenage Joan staring at her death pyre in The Passion of Joan of Arc.  Nothing funnier than the sight of Buster Keaton madly fleeing bees, bullets, boulders, and a mob of brides in Seven Chances.
 
Even if you never plan to direct a movie, never intend to know the difference between an f-stop and a long lens, as a screenwriter you need to think in terms of telling a story visually. It may help to compare movies to the stage.  In the fledgling days of filmmaking, movies were essentially filmed plays and that was mind-blowing enough for a while because the whole phenomenon of motion pictures was startlingly new. But soon filmmakers began to discover all kinds of tricks for telling stories in a more cinematic way. Here are probably the three most important tricks:
 
Cutting through space and time. Movies possess the godlike power to travel anywhere in the blink of an eye.
 
In luxurious headquarters at Cairo, a military officer receives a mission, lights a pipe for his superior, blows out the match. Then, hundreds of miles away, we see a flaming sunrise in the desert. Daylight then reveals the same officer, riding a camel across the sand, enroute to his new assignment.  (Lawrence of Arabia)
 
Moving the field of vision.  The camera can show whatever it wants to show.
 
Two outlaws come to the ledge of a towering canyon.  Far below, we see a river rushing over murderous rocks.  In the distance, we see a posse of lawmen riding toward them in pursuit. Then we see the rising panic on the outlaws’ faces. (Butch Cassidy and the Sundance Kid)
 
Special effects.  Nothing falls outside the reach of movie magic, and computer graphics have only expanded the possibilities.
 
Three men in sunglasses fire their guns at a hero in black, who holds up his hand. The spiraling bullets stop in mid-air, then tumble to the ground. The hero flies horizontally at one of the foes, disappearing inside his chest, causing him to distort, then emit lightning-like charges, then explode into pieces.  (The Matrix)
 
When movies gained the power of sound, that added a whole new dimension. Suddenly there was dialogue, of course, but you could also enhance the story with aural elements.  You could hear the gunshots and the rushing water and even hear the profound silence of the desert. Even so, visuals remain the most dominant element in movies. In fact, whenever you’re deciding how to portray a moment in your script, go first for the visual, following it up with sound effects or dialogue.  And really the art of film is the way these three elements—visual, aural, verbal—merge to tell a story, a story that seeps inside the viewers and makes them feel something.
 
This passage appears as part of Chapter 1 in Gotham Writers Workshop’s Writing Movies.