Unless we are talking about a precious few, we do not expect to hear Americans speak with insightful appreciation of Louis Armstrong. One reason Armstrong is not always understood correctly is that he was here, as he said, ''in the service of happiness.'' He was a one-man carnival of joy. Unfortunately, our aesthetic sense of tragedy and comedy, sorrow and happiness, derived from the Greeks, has convinced us that spiritual affliction is a more serious subject than spiritual exultation. I used to test this out when teaching the history of jazz years ago in California, where I would hold up a picture of Beethoven brooding and Armstrong smiling with transcontinental width. When asked which of the men looked like an artist, my students always said Beethoven. I told them that most people do not pursue the feelings that Beethoven struggled to express but tried their very best to get as close as possible to what Armstrong felt. In short, more endeavor is put into finding joy than unhappiness.

That is not to say that Armstrong was unaware of the feelings that are not joy. He grew up in abject poverty in New Orleans and found himself either a witness to or in the middle of cuttings and shootings. For a bit, he had a girl working the streets for him. He wasn't above putting his foot in somebody's behind if said guy went too far. His experiences with blues singers acquainted the young Armstrong with the failed love affairs that are so often their subject. In both New Orleans and Chicago, his profession often put him in the midst of violent men, thugs, gangsters and murderers. The tragic line of his trumpet playing on ''Tight Like That'' stretches for 30 years to connect with the deep song of the doomed or wounded heart that Miles Davis brought to ''Sketches of Spain.''

To get right down to it, no one in jazz ever played with greater emotional range than Armstrong, whose New Orleans experiences meant that he worked everything from christenings to funerals. In the streets, he picked up all the folk chants and bawdy songs. While traveling around town, he heard traces of French and Italian opera that suffused his sensibility and his memory. But beyond all that, what Armstrong wanted to give his listeners was the kind of pleasure music gave him, which is what most artists are after. When he wrote or talked of New Orleans, of being out there with his horn or following the parades or listening to mentors like Joe Oliver, Armstrong never failed to project a joy so profound that it became an antidote to the blues of daily living. We still understand him so poorly because of his determination to swallow experience whole and taste it all and only then to spit out the bitter parts.

Like D. W. Griffith, Armstrong was connected to all of the best and the worst of American culture. His refusal to ever stop being an entertainer made his connection to the minstrel tradition a little too much for those who were culturally faint of heart. He appeared to be too genial, too willing to accept film roles and tell jokes that many thought came too close to the gutter of burnt cork, red lips and imbecilic behavior. His innovations as a trumpet player and singer, once they had been absorbed, were ignored as his inferiors began to talk as if he were no more than the most famous Uncle Tom in the world.

Of course, by the middle 50's, when he had been largely dismissed by the younger generation of jazz musicians and was perceived as no more than a throwback to the plantation era, it was Armstrong alone who stood up and criticized President Dwight D. Eisenhower for not defending the black kids who were integrating Central High School in Little Rock, Ark. None of those others in the jazz world known for shooting their mouths off about race said a mumbling word. Armstrong had to stand out there by himself, something I'm sure didn't surprise him.

Any extended interview with Armstrong reveals the same thing that one learns from reading ''Louis Armstrong: In His Own Words,'' the recently published collection of his writings. Armstrong, like many people from New Orleans, had that Latin tendency to vendetta. He forgot no wrongs, but he tried to forgive. There were few he trusted, and his sense of the world was that it was a good place but would be a much better place if there weren't so many people out there trying to stab you in the back. At the same time, he was a big-hearted guy whose kind treatment of others is legendary in the world of show business. Few in the history of art have been so great and few have been so incompletely understood.