In 2006, The American Film Institute ranked “It’s a Wonderful Life” first on its list of the 100 most inspiring motion pictures ever made. To judge from the enduring popularity of the 1946 movie, which was directed by Frank Capra and stars Jimmy Stewart and Donna Reed, what it inspires in most viewers is optimism, gratitude, happiness: the Christmas spirit. But there have always been some who took a more jaundiced view of what has long been a beloved holiday classic.

J. Edgar Hoover’s FBI didn’t much care for it. In a 1947 memo on “Communist Infiltration of the Motion Picture Industry,” the agency quoted an informant’s belief that the malignant character of Henry Potter, played by Lionel Barrymore, “represented rather obvious attempts to discredit bankers,” which the informant called “a common trick used by Communists.” Yet The New Republic, which leaned sharply to the left, didn’t like it either. Its review mocked the movie as “the latest example of Capracorn” and an attempt “to convince movie audiences that American life is exactly like the Saturday Evening Post covers of Norman Rockwell.”

More recently, Salon magazine’s Gary Kamiya sneered that “when Marx penned his immortal words about ‘the idiocy of rural life,’ he probably had Bedford Falls [the town where the movie is set] in mind.” And in 2012 in the conservative Christian journal First Things, Notre Dame political scientist Patrick Deneen argued that George Bailey — the selfless protagonist of “It’s a Wonderful Life” — is actually an unwitting villain who hates his hometown and contributes to its decline.

To anyone expressing such cynical and withering views, I can only say: Try again — you can do better.

Which, more than any other, is the message that pervades “It’s a Wonderful Life.”

Rewatching the movie last week for perhaps the seventh or eighth time, I was caught up anew in the story of George, who has yearned all his life to travel the world and, as he tells the beautiful Mary Hatch, to “build things” — airfields, skyscrapers, bridges. But George never manages to leave Bedford Falls. His dreams never come true. At every step of the way, he chooses to put family and community responsibilities first. Struggling to keep afloat the small building and loan association founded by his father and uncle, he is thwarted by the rich and callous Potter, who has only contempt for George’s commitment to helping working-class residents buy homes of their own.

When a crucial $8,000 deposit goes missing on Christmas Eve, George knows that scandal — and criminal charges against him — are imminent. In despair, he considers throwing himself into the river. He wishes he had never been born. But a guardian angel arrives from Heaven and enables him to see how much worse off the world would have been without him. Eventually he breaks free of his suicidal wretchedness and realizes how much he cherishes his life, even with its disappointments. In one of the great lump-in-the-throat finales in Hollywood history, George’s friends and neighbors rally to replace the missing funds and show him that “no man is a failure who has friends.”

As I watched, I appreciated all the familiar themes of “It’s a Wonderful Life” — the richness of community, the efficacy of prayer, the power of love. Like the biblical Job, George confronts the inexplicable reality that the good sometimes suffer while the wicked thrive. And like Dorothy at the end of “The Wizard of Oz” — another cherished Hollywood classic — he finally learns that in seeking his heart’s desire, he needn’t look any further than his own backyard.

But for the first time, I was struck by another theme, one that surfaces repeatedly in Capra’s film: the importance of second chances.

The lives of numerous characters in “It’s a Wonderful Life” are transformed because they get a new start. George, who is ready to end his life because he thinks he is “worth more dead than alive,” in Potter’s taunting words, is only the most obvious example. There is George’s brother Harry, whom he saved from drowning in childhood — and who grew up to save the lives of hundreds of servicemen on a troop transport. There is also Mr. Gower, the pharmacist for whom George worked as a boy. At one point, Gower is so distracted by grief that he nearly poisons a family by botching their prescription, and when George intervenes he hits him hard enough to draw blood. In later life, Gower never forgets how much he owes George — and is among those who come through at the end to make sure the missing funds are replaced.

The same is true of flirty Violet Bick, slow-witted Uncle Billy, and Clarence, the “angel 2nd-class” who has been trying for centuries to earns his wings — in one way or another, all of them benefit from being offered another chance to make things right.

Even the dilapidated house that George and Mary move into after getting married — a waterlogged, broken-down old wreck known as the “Old Granville Place” — reflects the redeeming power of second chances. Early on, George disparages the house (“That place? I wouldn’t live in it as a ghost,” he says), but Mary sees the romance behind the debris. As George’s quest to travel the world and build skyscrapers comes to nought, the house becomes just another reminder of his frustrated ambitions. His wife, by contrast, sets about renovating the old heap. Painting the woodwork and putting up wallpaper, she steadily turns the Old Granville Place into a warm and cozy family home.

“It’s a Wonderful Life” provides one last example of how a second chance can transform failure and disappointment into success and joy — not a character or scene in the movie, but the movie itself.

Capra and the studio had high hopes for the film, but it opened to unenthusiastic ticket sales and lost $525,000 on its initial release. Though nominated for multiple Oscars, it didn’t win a single one. By the spring of 1947, “It’s a Wonderful Life” seemed washed up.

Then it got its second chance.

Through a clerical error in 1974, the film’s copyright wasn’t renewed. That put it in the public domain, which meant TV stations could air it for free. They began doing so, especially at Christmastime. Nearly 40 years after it flopped on the big screen, “It’s a Wonderful Life” achieved extraordinary success on the small screen. It had taken half a lifetime, but the picture that Capra always said was his favorite belatedly became one of America’s favorites, too. To the sour critics in 1946, it was all sentimental (or subversive) “Capracorn.” Yet three quarters of a century later, millions of viewers still watch, still wait for Clarence to get his wings, still tear up as George grasps how many hearts and lives he has touched. Our lives too have enriched, and been enriched by, the lives of others. May they continue to do so, in this season and every season.