These days, White travels back and forth from Houston, to which he relocated after Hurricane Katrina, and New Orleans, where he has a trailer near his office at Xavier. The flood destroyed most of what White had archived in his home in the Gentilly section of New Orleans, along the London Canal, a collection that would have made most museum directors green with envy: some 4,000 books, many rare; more than five thousand recordings, some quite obscure; transcriptions of music from Jelly Roll Morton, King Oliver, Sidney Bechet, and others; vintage clarinets dating from the 1880s to the 1930s; photographs, concert programs, and other memorabilia, including banjo strings and used reeds from early 20th century New Orleans musical heroes. But even before the storm, White saw a gradual fading away of musical tradition he'd been raised within -- the lineage of brass band players clad in white shirts and ties, with black-banded caps, playing everything from hymns to marches, blues to jazz with swinging rhythms, complex group improvisation and specific three-trumpet harmonies.

"There was something about that sound," White said dreamily when we spoke not long at his Xavier office, recalling the moment high-school band director Edwin Hampton played him a brass-band recording. There were more epiphanies to come for White: the first funeral he played with Doc Paulin's brass band; the recording he picked up on a whim, by clarinetist George Lewis, that turned out to be his most profound discovery. (For a great account of the impact of George Lewis and other traditional-jazz musicians, try Tom Sancton's book, Song for My Fathers.)

The Hot 8 Brass Band has its own story of continuation in the face of loss Three band members had died prematurely, two in violent circumstances. Another member lost his legs in a horrific roadside accident not long after Katrina hit. Finally, in January, during a wave of violent crimes, the group's 25-year-old snare drum player, Dinerral Shavers, was fatally shot in his car as his wife watched, by a teenager who was reportedly gunning for his stepson.

Last year, the Hot 8 manager, Lee Arnold began casual discussions with White about the need for younger brass-band musicians to connect with tradition-bearers.

Hot 8 founding member and tuba player Bennie Pete invited Dr. White if he'd like to begin working with the band for what grew into a series of workshops as well as performances.

"Bennie said, 'I'm tired of playing funk,'" recalled White, "which surprised me."

The informal workshops were a mixture of rehearsals and discussions about musical elements -- repertoire, harmony, dynamics, and so on -- but also about the history, social purpose, and shared values.

"I learned a lot about some things I had been uncertain about in the past," Peete told me in between sets at the café. "Answers to questions I'd never asked before."

But last night, the musicians -- ten strong, including the Hot 8, White, and guest tenor saxophonist John Gilbert (formerly of the Rebirth Brass Band) -- sounded anything but academic. "St. James Infirmary" moved from dirge-like to uptempo, and sweeping the crowd along in its mood shift. Keith "Wolf" Anderson's legs began kicking out from his chair as he blasted inventive lines with fury, and White's soloing was, by turns, sweet-toned, bluesy-curled, and dark-hued. (Still, as White and the Hot 8 members would be quick to point out, this music isn't about any individual solo; it's a collective statement.)

It was a buoyant statement of purpose and joy that would likely have blown out the café's shuttered doors, had they not already been open to the street, with musicians (including trumpeter Leroy Jones), hipsters and passersby leaning in, clapping syncopation into the muggy night air.