There is nothing harder to get right than a musical. Orbiting the earth? A monkey could do that—and has. But a great musical is achieved through unequal parts of talent, luck, and magic. Part of the magic comes from making it seem normal that halfway through a scene people stop talking to each other and sing the rest of their thoughts. Real people do not do that. But when someone gets a musical right, it is better than what real people do. Reality is what we have plenty of when we’re not watching something. A great musical is superior to reality.

Because they are so hard to realize, the list of great musicals is short. And there is no list of great musicals that does not have Singin’ in the Rain on it, usually at the top. Singin’ in the Rain turned 70 this year, yet it is ageless. It is indestructibly entertaining. It is very funny, with enough sentiment to lift your heart but not turn your stomach. The film is directed with great style by Gene Kelly and Stanley Donen, vividly shot by Harold Rosson, with witty costumes by Walter Plunkett. The four stars—Kelly as Don Lockwood, Debbie Reynolds as Kathy Selden, Donald O’Connor as Cosmo Brown, and Jean Hagen as Lina Lamont—were never better. The title song is one of the most charming numbers in film history, but there is musical glory throughout. Every 10 minutes or so, another jaw-dropping exhibition of talent arrives: “Fit As a Fiddle,” “Make ’Em Laugh,” “Moses Supposes,” “You Were Meant for Me,” “Good Morning,” and the astonishing “Broadway Melody Ballet.”

Gene Kelly and Debbie Reynolds on set.

Yet of all its virtues, the thing that makes Singin’ in the Rain arguably the best of all movie musicals is the screenplay by Betty Comden and Adolph Green. You can say this about very few musicals, but it is true about this one: you could take the songs out and the script is such a fine piece of comic and romantic storytelling, you would still have a crackerjack movie.

The impulse for the film came from Arthur Freed, who was the Midas of movie musicals. His first credit was as the associate producer of The Wizard of Oz, another candidate for the greatest screen musical of all time. After that, Freed was promoted to producer, and in the next 12 years, he produced, among other films, Babes in Arms, Strike Up the Band, For Me and My Gal, Cabin in the Sky, Meet Me in St. Louis, Easter Parade, Annie Get Your Gun, Showboat, and An American in Paris, for which he won his first Oscar. (He won again for Gigi.) Two of those hits—Easter Parade and An American in Paris—were based on songs from the catalogues of Irving Berlin and George Gershwin. So Freed cast his eye around for another catalogue, and this time it fell on his own. Before becoming a producer, he had been a successful lyricist, having written over a hundred songs in the 20s and 30s with the composer Nacio Herb Brown. Their biggest hit was “Singin’ in the Rain.”

So the movie Singin’ in the Rain was born not because there was a story that needed music, but because there was a lot of music that needed a story. Freed asked Betty Comden and Adolph Green to do the script.

Comden and Green had begun as performers. Along with Judy Holliday, they were nightclub entertainers in a group called the Revuers that performed satirical sketches and songs at the Village Vanguard in New York. When they were starting out, the Revuers couldn’t afford to pay for material, so, according to Comden, they chipped in and bought a pencil and wrote their own. Though Comden and Green would continue to perform on and off through the years, they owe their substantial place in show-business history to their work as writers. But their experience as performers richly informed their writing—their best musicals, Singin’ in the Rain and The Band Wagon, are set in show business and have a satirical yet sympathetic understanding of creative people.

When Freed offered them the project, there was no idea beyond using his songs and calling it Singin’ in the Rain. Comden recalled that for a long time, all they knew was that they were writing a musical and that, at some point, it would rain and somebody would sing in it. They spent hours with the musical director Roger Edens, who played them everything from the Freed-Brown catalogue. Hugh Fordin, in his book The World of Entertainment, says that as they listened to the songs, it occurred to them that the best of them were from the late 20s and early 30s, and rather than reconceive the songs in a sophisticated, contemporary story, why not keep them in their period? As it happened, that period was a momentous one in Hollywood history, the most momentous until television arrived: it was the end of the silent era and the beginning of sound.

You can say this about very few musicals, but it is true about this one: you could take the songs out and the script is such a fine piece of comic and romantic storytelling, you would still have a crackerjack movie.

Gene Kelly and Stanley Donen were set to direct (this would be their second picture as co-directors, after their debut with On the Town), but Kelly was shooting An American in Paris under Vincente Minnelli’s direction, so Donen worked with the writers.

Kelly and Reynolds in a publicity still.

“We ran a series of old Metro movies,” Donen said, “such as Platinum Blonde and Bombshell, to see if one could be made into a musical.” But those movies didn’t inspire anyone, and the group realized that instead of merely setting the story at the dawn of the sound era, the story should be about the dawn of the sound era, the frantic, almost overnight reworking of an entire industry—with all its comic possibilities.

Once they had that as their subject, Comden and Green found their story pretty quickly. Their work with the Revuers came in handy as they looked for ways to satirize the change from silent to sound. According to Andy Propst’s book They Made Us Happy, the Revuers had a sketch set in the same period that “included performers’ mouths being out of synch with their recorded dialogue and the unevenness of sound based on the performers’ proximity to unseen microphones.” (Surely one of the funniest, and naughtiest, lines in the movie is when Lina Lamont is instructed to pitch her lines toward the microphone, which has been hidden in a nearby bush. “Into the bush, Lina!” the director sputters at her. “Into the bush!”)

Green remembered the performance of the silent star John Gilbert in an early talkie, directed by Lionel Barrymore, called His Glorious Night. Either through the encouragement of his director or the bad work of the screenwriter, Gilbert had a love scene with Catherine Dale Owen, in which he said relentlessly, “I love you! I love you! I love you!” When Green saw the picture, the more Gilbert repeated the line, the harder the audience laughed. This, naturally, shows up in Singin’ in the Rain, with Don Lockwood saying “I love you” over and over to Lina in their film The Dueling Cavalier and the preview audience screaming with laughter.

It is after that disastrous preview that Don and Kathy and Cosmo go back to Don’s house to lick their wounds. Their moods change for the better when they come up with the idea of turning their flop The Dueling Cavalier into a musical, The Dancing Cavalier. In an earlier draft, to express their delight with this new plan, they sing “Singin’ in the Rain”—after all, it is raining outside. Luckily, the movie gods, who do not always pay attention (they were clearly on a lunch break when Julie Andrews lost the part of Eliza in the film of My Fair Lady), intervened. The song “Singin’ in the Rain” was saved for the following scene, when Don takes Kathy home and kisses her good night and then joyfully walks home in the rain. And in the slot originally occupied by “Singin’ in the Rain” went its radiant replacement, “Good Morning.”

So the movie Singin’ in the Rain was born not because there was a story that needed music, but because there was a lot of music that needed a story.

The movie gods intervened twice more, in matters of casting. Debbie Reynolds was not the first choice for Kathy—Ann Miller was originally announced for the role. Miller was a gifted dancer, but using her instead of Debbie Reynolds would be like replacing birthday candles with dynamite.

And for Cosmo Brown, the part played with a droll, featherlight charm by Donald O’Connor, Freed wanted Oscar Levant. Levant is an acquired taste that I’ve never acquired. As a comic actor, he sinks every laugh. Even by the loose standards of musicals, he’s always too broad. But Arthur Freed loved him. He had already used him in The Barkleys of Broadway (with a less suave script by Comden and Green) and An American in Paris and would use him again in The Band Wagon. Green once said, “Arthur Freed would have cast Oscar Levant as Huckleberry Finn if he could’ve gotten away with it.”

Knowing Levant well, Comden and Green tailored the part for him: Cosmo would be a pianist, as Levant was, who came up through the ranks with Don. According to Andy Propst, “they created a sequence in which [Levant] pitched the idea of a follow-up musical called The Piano-Playing Pioneer. As Cosmo described it to the head of the studio, a fantasy sequence unfurled in which Levant, playing the hero of the movie, subdued a murderous group of Native Americans with his rendition of a classical piece of music.” I’m not laughing already. Luckily, Levant withdrew from the project, paving the way for Donald O’Connor to take over.

Director Stanley Donen (center) with Donald O’Connor and Kelly.

It is almost impossible to overpraise O’Connor’s performance—he’s wonderfully funny, playful but not cloying, and he approaches his scenes like an actor, not a comic. Best of all, he is a sensational dancer. Think briefly—not too long, you’ll grow suicidal—if Levant had stayed on. It means we wouldn’t have had “Fit as a Fiddle,” “Moses Supposes,” or “Good Morning.” Mitch McConnell has a better shot at doing those steps than Oscar Levant. O’Connor more than holds his own with Gene Kelly, which is a titanic achievement. Normally when Kelly dances with a partner, you watch Kelly, and why not? It’s not a misallocation of your vision. But when Kelly dances with O’Connor, you go back and forth between them. Not only does O’Connor do everything Kelly does, but he does it without the self-enchantment that sometimes sours Kelly’s work.

The comic center of the film is the tin-voiced ham, Lina Lamont, played to perfection by Jean Hagen. Hagen’s first film role was just a few years earlier, in the Spencer Tracy and Katharine Hepburn comedy Adam’s Rib. You can see the seeds of Lina Lamont in her sly performance on the witness stand. But the other pictures she did were dramas, including The Asphalt Jungle, in which you can hardly believe this is the same actress who played Lina Lamont. Getting a great part in what turned out to be a classic musical was both a blessing and a curse for Hagen.

Astoundingly, the film received only two Oscar nominations, and she was one of them: for best supporting actress. (She lost to Gloria Grahame for The Bad and the Beautiful.) But other great film parts eluded her, and she was soon playing Danny Thomas’s wife on Make Room for Daddy. Though she was nominated for three Emmys, she found the part colorless and quit after the third season. Thomas was so mad at her that he had the writers kill the character off, giving her the oddball distinction of being the first character to be killed off in a family sitcom. Her real life was not much happier: alcoholism shadowed her; her husband divorced her and took their two children. She was dead at 54 of esophageal cancer.

There were some challenges filming the number “Singin’ in the Rain.” Kelly found it awkward to just start singing the song. “I always hated the Jeanette MacDonald-Nelson Eddy way of going into a song,” Kelly explained, by which he meant just launching into it, like a proclamation, not a discovery. “[So] Roger [Edens] came up with a solution,” Kelly explained. “Start off with doodedoo do doodedoo do.” He found a way to tiptoe into a masterpiece.

After the set was built on MGM’s East Side Street, Kelly did the number for the set designer Randall Duell, showing him exactly where he wanted to splash water with his feet. Duell then marked the spots with chalk, and those areas were hollowed out so that water could accumulate in them. Their first “wet” dress rehearsal of the number was at five in the afternoon, and as the number progressed, the rain grew weaker and weaker until it was just spitting. The water was supplied by the town of Culver City, and as it turned out, at five o’clock on a hot summer’s afternoon, a lot of people turned their sprinklers on, so there was a drain on the system. All was addressed for the time of shooting. The number took a day and a half to film.

When O’Connor came into the picture, there was nothing in the Freed-Brown catalogue that was suitable for him, so Stanley Donen went to Freed and asked for a new song. They needed something for a spot where Cosmo is trying to cheer Don up. Donen referenced Cole Porter’s song “Be a Clown” from The Pirate.

After the set was built on MGM’s East Side Street, Kelly did the number for the set designer Randall Duell, showing him exactly where he wanted to splash water with his feet.

Freed came back quickly with “Make ’Em Laugh”—too quickly. It is almost note for note, and thought for thought, “Be a Clown.” “100% plagiarism,” Donen said. When the number was being shot, Irving Berlin was visiting the set and was shocked at the xerox-like similarities. Berlin was a close friend of Porter’s and called Freed out. “I’ve never heard anything like that in my life!” He demanded to know who wrote it, and Freed sputtered, “The kids and I!,” even though “the kids” had nothing to do with it. (Porter generously never made a fuss about this.)

Kelly with Cyd Charisse.

The biggest number in the film is “The Broadway Ballet,” which contains the rallying cry for dancers everywhere, “Gotta dance!” It is almost 15 minutes long, and there are a number of arguments to be made against it: it’s modern and the rest of the movie is set during the French Revolution; it’s much longer than any other number in the movie and has nothing to do with the plot of either The Dancing Cavalier or Singin’ in the Rain. It’s just an excuse to show off Gene Kelly. Yet there are few people more worth showing off than Gene Kelly, unless it is Cyd Charisse, who joins him with scintillating effect halfway through. The dancing is imaginative and prodigious, buoyant, sexy, and joyful. The sets for its numerous locations were originally budgeted at $80,000. It ended up costing $600,000. They rehearsed it for a month, and it took two weeks to shoot. As you watch it, if you are churlish enough to have anything so pedestrian as a logic problem, you surrender to the artistry, not the artiness, of it, and revel in its sumptuous imagination and the talent it takes to make it look so easy.

Here’s a wonderful detail. A lot of the movie is about Debbie Reynolds’s character, Kathy, dubbing the voice of Jean Hagen’s character, Lina, replacing Lina’s off-key caterwauling with a more refined, mid-Atlantic sound. But Stanley Donen said that they actually had Jean Hagen dub Debbie’s voice dubbing Jean. “Jean’s voice is quite remarkable,” Donen said. “It was supposed to be cultured speech—and Debbie has that terrible Midwestern noise.” In the movie, when Reynolds dubs Hagen’s singing “Would You?” behind the scenes, Reynolds’s voice was actually dubbed by Betty Noyes.

This is why we love the movies—layer upon layer of deception in the service of our happiness. And this is why we love Singin’ in the Rain. It charms the shallow (me) and the deep alike: at a party in Paris, François Truffaut rushed over to Comden and Green, thrilled to meet the writers of Chantons Sous la Pluie. He said he had seen the film so many times, he knew it frame by frame. He and Alain Resnais used to see it regularly in a small theater where it ran for months at a time.

Truffaut knew what anyone who sees Singin’ in the Rain even once knows: everything in it is constructed to delight us, and everything in it does. Happy 70th, you fleet-footed, heart-lifting masterpiece!

Douglas McGrath is a filmmaker and a playwright. He wrote the book for Beautiful: The Carole King Musical