The wedding scene in ‘The Godfather’ is a masterclass in establishing a film’s narrative. Here’s why.

The mark of a great screenplay is a film’s ability to show, not tell. To describe the motives, personalities and attitudes of a character not through exposition, but their actions. Films feel more organic that way – breathing, believable narratives versus a checklist with tasks that writers laboriously mark off.

Character-building is a huge part of that endeavor, bringing creations to the screen, not cardboard cutouts. There isn’t just one way of doing it, either. Aaron Sorkin brings his characters to life with his patented “walk-and-talk,” fiery and furious conversations between characters that reveal the inner workings of their psyches.

There’s also writers like the Coen brothers, who – in contrast to Sorkin – create characters that are deliberate almost to a fault in their words and actions as they traverse worlds that are typically paranoia-filled.

Then there is Francis Ford Coppola, the maestro behind “The Godfather” saga and “Apocalypse Now” who seems to know the characters he’s writing like he befriended them as a child.

Like Hollywood’s best writers throughout history, Coppola wrote characters in a way that wasn’t just thrilling and engaging, but earnestly – and sometimes devastatingly – honest. The respective journeys of Don Corleone, Michael, Captain Benjamin Willard and Colonel Kurtz were dark and deeply introspective.

And it was because of the way that Coppola wrote them – along with some excellent casting choices – that these characters are timeless and endearing, eternally iconic.

One scene in particular showcases Coppola’s abilities as a writer (as well as a director, but that’s another story) better than perhaps any in his arsenal. It’s a nearly half-hour-long sequence that sets the stage for what many consider to be the greatest trilogy in history.

Connie’s wedding — the opening scene of “The Godfather Part I” — is a masterclass in screenwriting. It’s equal parts comedy, horror and drama. Coppola does no telling about the type of people Don, Michael, Sonny, Kay and company are. He shows us, using exquisite attention to detail and a tone that is so matter-of-fact that, even after a lifetime of watching and rewatching the film, it’s easy to experience the wedding and forget these are people who would do anything for the family, including shed blood.

We get a look at everyone here, and – save for Michael in his Golden Boy state before spiraling down the same path as the rest of his family – they’re all true to form to a particular degree.

The hot-tempered and licentious Sonny breaks an FBI agent’s camera before throwing a couple hundred bucks at his feet, in a way that shows he doesn’t take back his actions.

Tom Hagan is even-headed and cool, the mild-mannered family lawyer who is always at the Don’s side and who speaks with voice so collected it instantly informs us why he fits right in with the Corleones, even if he’s not a biological member.

Kay is timid and curious about Michael’s family, then caught completely off-guard when she – and us as the audience – learns from Michael about the fabled offer that couldn’t be refused.

And, of course, Marlon Brando’s transcendent Don Corleone is grandiose and threatening, yet not without the gentle and homely qualities of our own grandfathers. He pets his cat. He commands loyalty. He slaps around his godson for not standing up for what he wants. He just wants to celebrate on the day his daughter is to be wed, but he knows what that means in Sicilian tradition.

More than anything, he just wants a picture with the whole family.

Who can’t relate to that?

Perhaps the element that makes the wedding scene one of the most critically important when viewed in the context of the trilogy at large is that this is the one afternoon we can spend with these characters that is free of impending bloodshed and death.

Another half-hour on, and we’ve seen a beheaded horse, a man be strangled and a viscerally depicted attempt on the Don’s life.

But for these few, precious moments, these are just the Corleones on a wedding day that is seemingly as normal as any we’ve been to.

The sequence is filled with elements that are simultaneously iconic but also so ordinary. The cat. Johnny Fontane making the young ladies swoon. Pauley with the wine. Coppola is able to incorporate all of that to help paint – in brushstrokes both broad and intimate – an image of a family that is like any other, their criminal underworld business dealings non-withstanding.

Then, before you get too ostensibly comfortable, Coppola slips subtle elements in – like a shot of the intimidating Don Barzini, the matter-of-fact assassination assignments by the Don, or the origin story of the offer that couldn’t be refused – that keeps the pedal at least somewhat to the metal.

The scene is a contract of sorts. An establishing of the stakes. Coppola is setting the table for a dinner from hell. Once we get to the Don dancing with the bride and the scene winds down, we’re strapped in.

“Keep your arms and legs inside at all times,” Coppola is saying. “That’s as pleasant as this ride is going to be.”