By Jeff Chang

ALL GREAT ISLAND music stories seem to begin with a throwaway instrument and its brilliant adaptation. Promoted by German manufacturer Hohner as a music educator's tool during the '50s, the melodica is kind of a plastic hybrid of harmonica and piano. Its fragile, whispy tones have graced music by artists as diverse as Don Cherry, New Order, and the Apples in Stereo. But more than anything else, the sound of the melodica signifies dub reggae, thanks to the late Jamaican great Augustus Pablo. His mastery elevated the cheap instrument from a child's plaything to a tool for art of consequence and transcendence.

Born Horace Swaby to South Asian and black parents in a Kingston suburb, Pablo began as a soundboy on his own Rockers sound system. One day he asked a buddy's girlfriend if he could borrow her melodica. While Pablo was playing it outside the famed Aquarius Records shop, proprietor and producer Herman Chin-Loy, looking for a new sound, heard him and asked him to sit in on a session. The stunning "East of the River Nile" was the result.

The song already had an astounding pedigree: Chin-Loy had bought the riddim from Lee "Scratch" Perry. Its bass line was almost James Brownian. Earl "Chinna" Smith added a frantic guitar line, and Pablo floated an airy counterpoint. J-Live recently interpolated it for "Satisfied," one of the best hip-hop singles this year, with Victor "Ticklash" Axelrod (Antibalas, Roots Combination) playing Pablo's part.

Shanachie's rerelease of the East of the River Nile album offers the original single and two additional album versions. Play all of them back to back; the groove sounds as uplifting now as it was groundbreaking then. The album, offered in a definitive edition with several extra dubs and rare tracks, remains landmark, the peak of Pablo's "Far East" instrumental sound.

Like Miles Davis, Pablo was stingy with his notes, giving the earthy riddims an airy feel. Check the way the crawling tempo of "Natural Way" lightens thanks to Pablo's subtle touch on the melodica and the clavinet. He clearly shared the dubmasters' love of contingency and the dub fanatics' thirst for endless versioning. He played as if he were awed by the myriad answers available for any musical problem. Pablo's music deliberately left a lot to the imagination, always let you hear the unheard. In an interview with U.K. dub outfit the Disciples for their Web site, he said, "Everybody used to say our music is unfinished. In America they used to say that, years ago." Racist critics stuck on the Eric Clapton cargo cult saw Pablo with a big chalice and assumed he was too stoned to finish his tracks. Postmodern hip-hop and dance producers have left Pablo with the last laugh. (The wry, cerebral track that bears the name "Unfinished Melody" demonstrates just how similarly Pablo and Lee "Scratch" Perry thought.)

Pablo's most celebrated album justly remains King Tubby Meets the Rockers Uptown, but Original Rockers, recently rereleased by Greensleeves with two new dubs, is just as good. Mixed by Tubby, Philip Smart, and Prince Jammy, the album features the same kind of engaging bass-and-drum grooves, but with a beguiling twist. Where Rockers Uptown signified disintegration, Original Rockers imagines rebirth. The famously frenetic version of Rockers Uptown, released as political violence began to peak in Jamaica, featured Jacob Miller's glorious voice foreshortened to stammers of unfulfilled desire. It sounded like nothing so much as armagideon time, as complete social collapse.