Memory is a merciful thing when it comes movies. We remember the grand moments in films, the signature bits, and much of what’s less moving, entertaining or important just drifts away.

Charlie Chaplin had become Charles Chaplin long before “Limelight,” a grand old man (he was over 60) of silent and sound comedy, of vaudeville before that and of the English music halls which gave him his start and first taste of fame that was to grow until his was the most recognizable face and mustache in the world.

But he’d followed his father, a somewhat famous British singer and mimic, into those music halls. And he’d seen what changing tastes, declining status and obscurity did to show people. Crushed pride was the least of it, and alchoholism was often a consequence.

“Limelight” is a somber, sentimental and seriously old-fashioned melodrama, a lumbering, under-edited meander through the English music hall life of the early 20th century, when cinema first showed up to announce its eventual death.

But what we remember about it is the magic of the two greatest silent film comedians, Chaplin and Buster Keaton, sharing a few scenes late in the film, recreating a little of the earlier slapstick and mimed magic from their days treading the boards, living out of a trunk before the movies and Hollywood lured them West.

Chaplin’s movie is a literal relic, a far less edgy, dynamic and cinematic experience than “The Entertainer,” a blast of the new “kitchen sink realism” that scorched some of the same ground less than a decade later, and more sentimental and far less amusing than “Stan & Ollie,” the most recent film to reach back into that world.

The camera is anchored and static, with pristine, lifeless Hollywood backlots doubling for London streets, and mostly spare sets (and painted backdrops) for scenes often allowed to play out in a single long take.

That was a remarkable trait of Chaplin’s silent classics, as we see the clockwork comedy of a genius of the pratfall and near-pratfall dodge blows, gigantic machinery and automobiles and show off just how completely he’d mastered roller skates. But editing is what animates cinema, and “Limelight” only allows it when the star needed another take on that last bit, or decided a close-up is necessary.

He’d mercifully turn away from the hokey suicidal-dancer-who-won’t-dance plot to deliver entire music hall routines, corny songs, understated dances and dated monologues that preserve the institution he was celebrating — in amber.

But as the melodrama progresses and ballet-with-slapstick moves center stage, as the faded “star” Calvero’s “comeback” begins, “Limelight” livens up. By the time Keaton shows up we get why this picture, which earned plenty of indifferent reviews upon release, has come to be celebrated as Chaplin’s last “great” (almost) movie.

Calvero used to be a top-of-the-marquee “tramp act” in the music halls. We meet him drunk, having whiled away a night in his cups with his fellow unemployed old timers in 1914 London.

He smells gas upon finally making his way past the lock on his apartment house’s front door. And after elaborately checking his shoes to ensure he hasn’t stepped in something, spies a downstairs flat with towels stuffed under the door.

The gamine (Claire Bloom) has tried to kill herself — drinking poison, turning on the gas. Calvero rescues her, fetches a doctor and even talks the unsympathetic landlady (Marjorie Bennett) into letting her stay with him to recuperate, something the doctor ordered.

Thereza or “Terry” is broke, a dancer who can’t dance thanks to a bout of rheumatic fever. The doctor sets Calvero straight. She probably didn’t have rheumatic fever. This “can’t use my legs” thing is all in her head.

“Are you in pain?” Calvero asks. If not, “the rest is fantasy.”

It’s hopeless, she insists.

“Then live without hope. Live for the moment. There are still…wonderful moments!“

He dreams of a stage collaboration between them, but once awake he has accept the honesty in her “No one would ever think you’re a comedian.” He’s not funny, not while sober, anyway.

His agent (Barry Bernard) insists his name is “poison” to theater bookers. But as Calvero reaches his low ebb, at least he’s encouraged Terry to begin anew. She joins a dance company, and her director (Hitchcock favorite Norman Lloyd) and the producer (Nigel Bruce, Watson to Basil Rathbone’s Sherlock Holmes) have a ballet in mind, a “harlequinade,” that requires clowns.

Maybe Terry knows someone? And if she freezes up before dancing onto the stage, he’ll be right there to slap her back into reality. (Ouch)

Chaplin’s direction seemed more and more old-fashioned and lackluster the longer he directed and the more the cinema “grew up” and grew more visually sophisticated around him. The best images are in his real-time treatment of the ballet, as he uses crane shots to show the silent, efficient bustle of scene-changes in a theater.

Chaplin won his only competitive Oscar as a very old man, as “Limelight” wasn’t properly released in the U.S. under Academy rules, and the Best Original Score Academy Award (1973) came to the film after its “official” L.A. release in 1972. “Terry’s Theme,” also known as “Eternally,” is one of the most recognizable melodies in screen score history.

His acting was always presentational, closer to mime than “Method.” But the performances surrounding him here are pretty good, with Bruce, Lloyd and other veterans in top form and relative-newcomer Bloom holding her own and Chaplin’s son Sydney Chaplin not bad as the composer/love-interest who might turn Terry’s head away from the elderly savior she’s “fallen in love” with (Um, ok).

The real magic here is where it always was, putting two legendary troupers together in a dressing room, on a music hall stage, performing shtick (not exactly hilarious). They remind us of the nerve and craft that it takes to do it and that while tastes in comedy change, old tramp comics never die. Not while there’s a film camera around to catch them at their peak.

Rating: “approved” (G)

Cast: Charles Chaplin, Claire Bloom, Nigel Bruce, Sydney Chaplin, Norman Lloyd and Buster Keaton

Credits: Scripted and directed by Charles Chaplin. A United Artists release on Tubi and other streamers.

Running time: 2:17