The immortality conferred on composers may be the sweetest immortality of all. No one can hum a Picasso while picking out eggplants at the supermarket. In his lifetime, Jerome Kern could never know into how many minds on the planet Earth a Jerome Kern tune might have popped at any given moment. One hundred years after his birth, nearly 40 after his death, we are still in his lifetime. We still hum his tunes.

A composer's lifetime doesn't really end until all the humming ceases. In the case of Jerome Kern, no one can look that far into the future.

Perhaps at some point in that future, science will manage to break down all of what we now consider creative gifts into terms of chemical interaction and genetic confluence. In what molecule does a melody start? Can it be artificially produced in a laboratory? (It must be a Jewish molecule, since most of the great pop composers of Kern's era, with the conspicuous exception of Cole Porter, were). We can't dissect, much less synthesize, a "God-given talent" yet. So for now we have to be content with a less precise, much sloppier, explanation: it's a miracle, and the people on whom it is visited are damn lucky.

Certainly miraculous melodies poured from Kern's brain. If he had only written "Ol' Man River," we probably would still be remembering him today. But he also wrote "Smoke Gets in Your Eyes," "The Last Time I Saw Paris," "The Way You Look Tonight," "Dearly Beloved," "The Folks Who Live on the Hill," "Yesterdays." He wrote "The Song Is You." The song was him.

Reputedly obsessive in the way he honed and hammered each song into a gleaming, seamless chalice, Kern's best have a pristine, natural grace. If Ira Gershwin had not written words to "Long Ago and Far Away," Kern's tune would still convey wistful reminiscence. But Gershwin's lyrics weren't from hunger. "Chills run up and down my spine, Aladdin's lamp is mine" -- this was a sublime collaboration.

Kern's most romantic work could support lyricists' allusions to things like "the promised kiss of springtime," "the breathless hush of evening," "the angel glow that lights a star," "the sound of rain upon a window pane," "the starry song that April sings."

This year's fancies, are passing fancies, but sighing sighs, holding hands, these a heart, understands. That's Johnny Mercer paraphrased by way of explaining why we still sing the praises of and the songs of Jerome Kern.

Because Kern, like his friend the great George Gershwin, went Hollywood, there are permanent records of vintage Kerniana performed in context. "Show Boat" was filmed several times. The best version was made by, of all people, James Whale, the director of "Frankenstein." Its grievous racial stereotypes aside, the film makes a priceless record of musical history.

And it includes not only Helen Morgan's version of "Can't Help Lovin' That Man" (sung up-tempo, as it was meant to be), but also Paul Robeson's "Ol' Man River." Whale was obviously and understandably mesmerized by this giant, brilliant spectre -- the camera encircles Robeson as he sits on a dock through the first chorus -- and the full force of the song's power comes through.

The two best movies with original Kern scores were both made at Columbia during the war and both starred Rita Hayworth, the goddessy vision oddly absent from MGM-UA's lackluster compilation picture "That's Dancing." In "Cover Girl," Gene Kelly sang "Long Ago" to Hayworth and they danced to it in an empty nightclub. Another number, "Sure Thing," is one of the overlooked Kern gems. But it's the finale, "Make Way for Tomorrow," danced by Hayworth, Kelly and Phil Silvers, that is probably most memorable, mainly for its infectious optimistic bravado. Tomorrow, of course, the war would be over. And everything would be peachy.

In 1942, Fred Astaire twirled Hayworth through "You Were Never Lovelier," which surmounted a contrived romantic-mix-up plot on the basis of Astaire's charm, Hayworth's willowy beauty, and a Kern score that was perfect down to the last dot next to the last quarter-note. The title song, "Dearly Beloved" and "I'm Old Fashioned" became hits, but even an incidental expository trifle, "These Orchids If You Please," sung by bellboys delivering flowers to Hayworth, has a rich, dreamy glow.

Only in recent years has a print of "Cover Girl" in its original Technicolor become available for general theatrical and TV viewing, but a spokesman for RCA-Columbia Home Video in Los Angeles says there are now (incredibly enough) no plans to release the film on Beta or VHS tapes. However, "You Were Never Lovelier" has, fortuitously enough, just been shipped to stores and should be available soon.

Of the Kern hommage recordings recently released, last year's "Silver Linings," with soprano Joan Morris and pianist William Bolcom, may prove unsurpassable. Marred by the occasional smugness, the album, available on a glistening Arabesque compact disc, includes such invaluable delicacies as Kern and Otto Harbach's elegantly poignant "Poor Pierrot" (sung almost as well as Mabel Mercer sang it) and a true discovery, "Lonesome Walls," a blues aria with lyrics by DuBose Heyward ("Porgy and Bess") that was written as mere source music to be overheard from an onstage radio in the non-musical play "Mamba's Daughters" with Ethel Waters.

In his day, Kern had great fame and success, but it's sometimes disconcerting to see that he and Gershwin and Berlin and Porter weren't treated more royally than they were. They all had their flops and misfires, but what a privilege to have lived at a time when talents so prodigious were in flower. People didn't know what they had. They just didn't know.

In Milton Babbit's musicological liner notes for Morris-Bolcom, he praises the structure of "Long Ago" for "its singular chorus of four parallel musical statements: the first and third in the tonic, the second and fourth on the third and fifth of the minor tonic triad of the piece . . ." Oh yes. Right. Then I listen to the song and I have another reaction: Chills run up and down my spine. Aladdin's lamp is mine.

The dream I dreamed was not denied me.

Wake up, Mr. Kern. Wake up. Wake for a tiny moment and listen to what the world is singing. The song is still you. What you did wasn't just good, Mr. Kern, it wasn't just craftsmanship. It was art. Maybe if the genes and chromosomes and chemicals and environment had all interacted in some crazy other way, you might have been the one to split the atom. But you were lucky. You wrote songs instead.