The classic “It’s A Wonderful Life” began as a box office flop that was dismissed by critics as “embarrassing.”

Everyone knows the famous phrase: “Every time a bell rings, an angel gets its wings.”

But there’s an even more inspiring message from Hollywood history: Sometimes, when a movie is a failure, it gets a second chance.

Amazingly, that’s what happened with It’s A Wonderful Life, Frank Capra’s classic that many now consider to be the best Christmas film of all time.

You’d never know it from the fame and ubiquity of the esteemed title, but the film, starring James (Jimmy) Stewart and Donna Reed, wasn’t a huge box office success in its day and was met with a shrug from many critics who also loved it carefully juicy.

“(Capra) strives for the big, meaningful feelings and avoids falling into embarrassing theatrics,” wrote Archer Winsten in The Post.

“The weakness of this picture, in this reviewer’s view, is its sentimentality,” reiterated Bosley Crowther in the Times.

George Bailey would eventually become the richest man in town. However, after almost being lost to history, it lasted for more than 30 years.

When “It’s A Wonderful Life” hit theaters on December 20, 1946, it wasn’t inherently unpopular. The glittering premiere took place here in New York at the Globe Theater on Broadway (now the Lunt-Fontanne, home of the musical Death Becomes Her).

The acclaimed director’s film “It Happened One Night” grossed $3.3 million at the box office – a strong success under most circumstances.

The problem is that Capra’s budget had exploded and the film had to make almost double that revenue to break even. It’s A Wonderful Life, one of only two films from Capra’s Liberty Films, failed to recoup its high costs. In short, it was a flop.

Still, the film was nominated for five Oscars – including Best Picture, Best Director and Best Actor – but won none. The big winner at the Academy Awards and at the box office was William Wyler’s consistently brilliant film The Best Years of Our Lives.

How could “Life” become so wonderful?

In 1974, the copyright to Capra’s film was up for renewal – at that time each term lasted 28 years – but the owner Republic Pictures mistakenly allowed the property to become public property. Suddenly everyone could broadcast it for free.

And they aired it. The heartwarming Jimmy Stewart’s frequent TV broadcasts were popular with baby boomers in the mid-1970s, who had very different tastes than their Silent Generation parents. Capra’s film was given another chance and exploded.

“It’s the damnedest thing I’ve ever seen,” the director told the Wall Street Journal in 1984.

“The film now has a life of its own and I can look at it as if I had nothing to do with it. I’m like a parent whose child grows up to be president. I’m proud… but it’s the boy who did the work.”

By the way, “It’s A Wonderful Life” is again about making money. The Republic took its case to the Supreme Court in 1993 and regained the lost copyright. Paramount then purchased Republic in 1998.

This year, countless families will sit together to watch the real festival, whose director surprisingly had no big Christmas ambitions.

“When I first came across it, I didn’t even think it was a Christmas story,” Capra said. “I just liked the idea.”