My favorite movie is Frank Capra’s immortal It’s a Wonderful Life, which celebrates its 70th birthday December 20, 2016.

Sure, there are better-made films. And, yes, there are far more influential ones. It’s a Wonderful Life’s status as an American classic is owed largely to a quirk of paperwork — after National Telefilm Associates, which owned the film after a long, convoluted chain of corporate sales, failed to renew its copyright in 1974, the movie fell into the public domain. Local TV stations found it to be a good way to paper over the long winter afternoons of December, their viewers discovered how good it is, and it became the classic it is today.

But if you were to tell Capra back in the late ’40s that his film would go on to become a perennial favorite, he might have scoffed at you. Upon release, It’s a Wonderful Life was greeted with weak box office earnings and reviews that amounted to, “It’s fine, but nothing special.” Though the film was nominated for a handful of Oscars (thanks mainly to Capra’s prestige within the industry at the time), it lost to William Wyler’s The Best Years of Our Lives, also a terrific film.

Weirdly, It’s a Wonderful Life seems to be slipping back into the mists of time. It’ll never be as forgotten as it was before that paperwork mishap, of course, but in recent years it’s been replaced in popular discourse by a new series of Christmas movies, like A Christmas Story and National Lampoon’s Christmas Vacation. Now that NBC owns the exclusive rights to broadcast the film, it’s less ubiquitous, just another annual tradition.

It would be too bad if the film lost its cachet, though. It’s a Wonderful Life is one of the best films America has ever made about itself, and that’s why I love it so much.

It’s a Wonderful Life belongs to a very specific subgenre of popular American art

In the wake of World War II, many Americans were struggling with a very specific sort of mental hurdle. The evils of fascism had been defeated, and everyone could agree that was good. But there was a constant question of just how great the ultimate cost would be. Men had died in battle, and many of those who returned home were wracked with mental anguish over what they had seen and done.

Today, we would recognize this as PTSD, but post–World War II America didn’t have such a clinical diagnosis. So some people tried to understand the horrors these men had experienced — and their desires to plunge headfirst back into normalcy — via art. These are stories about men coming home from war and trying their damnedest to make their sacrifice worth something, by making the country a better, more moral place. And often the characters fail — on both personal and societal levels.

Indeed, the period from 1945 to 1960 is one of the greatest in history in terms of mainstream, popular American art wrestling with the grimmer sides of the American dream. (It was also, not coincidentally, the period of the House Un-American Activities Committee and the Hollywood blacklist.) This is the era that produced Ralph Ellison’s tremendous novel Invisible Man and the early works of writers like John Updike and John Cheever. It’s the period of the first golden age of television and the last golden age of radio.

It’s also my favorite period for Hollywood films. Film noir and the Western were both fully flourishing, willing to tackle the darkest sides of their big-screen myths, and even the musical found bittersweet morsels amid all that cotton candy.

But It’s a Wonderful Life stands apart for many reasons, not least of which might be that it was made by two men who were returning home from war themselves. Both Capra and star Jimmy Stewart had been to Europe, had put their careers on hold to help the war effort. (Stewart flew combat missions; Capra made documentaries, including the famous Why We Fight.) And though neither was, say, actively leading the push toward Berlin, both were present for some of the Allies’ darkest hours and their eventual triumph.

Watching It’s a Wonderful Life in 2016, it’s easy to forget that when it was released, it was at least partially a period film. Capra and his team are looking back on roughly 20 years of history leading up to the moment of the film’s debut. It takes in the highs of most of the ’20s and the lows of the Depression. By the time it gets to World War II — well over halfway through the film — you get the sense that its characters aren’t sure they’ll ever find peace. The war effort is viewed as an obvious good, but its effect on the young men of Bedford Falls (including George, who can’t go into battle) is treated with more ambivalence.

It’s almost a cliché to note that It’s a Wonderful Life is a darker film than its feel-good reputation might suggest. It is, after all, a movie about a man who puts his dreams on hold, again and again, for the betterment of his community.

But when you view the film through the prism of its origins — in a nation that had just been through so very, very much — that reading becomes more poignant. Time and time again, America, like George Bailey, had been asked to set aside other goals to respond to crisis. And time and time again, it had done so.

But for what purpose?

It’s a Wonderful Life is a not-so-subtle argument for New Deal values

The last time I watched It’s a Wonderful Life was this spring, on a massive screen during Turner Classic Movies’ 2016 festival. Watching it on such a big screen, something became evident: Capra was immensely skilled at putting lots and lots of actors in the frame and giving them all something to do.

Take this shot from George’s wedding to Mary Hatch (Donna Reed), the girl he’s obviously been perfect for since both were children. Look at how many actors Capra crams into the scene, and how you instantly understand their relationships not just to each other but to George and Mary’s wedding.

And here’s another, from earlier in the film, when George and Mary get reacquainted at George’s brother’s high school graduation party. Again, the focus is on Reed at the center of the frame, but all the other players have space to shine.

This approach also extends to scenes with very few actors in them. In the video below, for example, George is realizing just how deeply he loves Mary, after spurning her moments earlier. Capra films their phone call in a single shot, allowing Stewart and Reed’s eyes to keep drifting toward each other, trusting the actors to keep the story moving.

The effect subtly underlines It’s a Wonderful Life’s not-so-subtle theme — that we are only as good as our ability to connect with those around us. The film’s main villain, after all, is a corrupt old banker who would turn Bedford Falls into his own personal playground, and George succeeds in leading the fight against him less because of his business acumen (though he has plenty) and more because his natural tendency to stand up to despots gains him friends and allies across all sorts of boundaries.

Contrast the community-oriented shots in the early sections of the film with the way Capra isolates many characters in the film’s final quarter, after George, with the help of an angel, travels to an alternate reality where he had never been born.

In the early going, even when the shot is focused solely on George, Capra often places some other recognizable faces in the background — the moment might be our hero’s, but there’s always someone else around who’s worth working with or worth fighting for.

In the alternate reality, however, George is often filmed alone, or with faces in the background blurred out. Some of that is because he’s in a world where he doesn’t belong, where even Mary doesn’t recognize him. But some of it is because he’s forsaken his truest calling: helping others.

In this sense, It’s a Wonderful Life is also about why America was worth fighting for. The characters turn back a war abroad, but they must constantly keep fighting the war at home, to make sure the nation continues to stand for what it says it believes in. In It’s a Wonderful Life, the American dream isn’t an endpoint; it’s something no one person can possibly attain, because its best possible version forever lies in the future. But we struggle forward, keep doing better, keep trying to build a more perfect world.

It’s a Wonderful Life is a message in a bottle

You could not pick two better works of art to send into the future to express American hopes and anxieties in 1946 than It’s a Wonderful Life and the year’s Best Picture winner, the aforementioned Best Years of Our Lives. Both films expertly contrast the American small-town ideal with its occasional failures to embody its best self. Both films wonder what’s next for the nation after more than 15 years of turmoil. And both films cast a hopeful, wearily optimistic eye toward the future.

But both films also revolve around a very potent idea of what America is and what it can be: a force for goodness. Neither is so naive as to think that by winning World War II, America has finally vanquished all claims against its moral authority. They believe America is at its best when it tries to be its best.

It’s a Wonderful Life, in particular, does not suggest this is easy. George Bailey averts jail time as the film ends, thanks to all of his friends. He will remember their selfless act for the rest of his life, but that feeling will fade and grow patchy with time. It’s a wonderful life, sure, but you have to keep reminding yourself of that fact, because sometimes it’s anything but.

The movie ends on a moment of bittersweet catharsis but is also wise enough to know that life is long, and life is often disappointing.

On Christmas morning in 1947, 1958, 1972, George will wake up, with less and less of that memory ringing in his brain, and might be tempted to despair again, to throw away his life or what he holds dear. George never did leave Bedford Falls. He never attained his most deeply held dreams. He got stuck, and that’s difficult to discard.

But what you do when you’re stuck is often the best example of who you truly are. It’s a Wonderful Life isn’t an argument that George is a morally superior man, just that he’s a moral man, surrounded by other moral people, and moral people try to take care of each other. The great kindness paid to George at the end of It’s a Wonderful Life suffuses every frame that came before that moment. It’s baked in.

Capra and Stewart, back home after the world nearly threw itself off a cliff, knew how easy it is to destroy our best qualities. They knew that humanity is only as good as it is kind, and they made a film about just that. Here, in 2016, 70 years later, it bobs up to us like a message in a bottle from the past. Do not let cruelty win, it says. Reach out. Hold on. Help.