When I was a young boxing writer, I once was invited to watch historic fight films with a small group that included Sugar Ray Robinson, by then long retired from the ring.

Suffice to say, I was -- by several orders of magnitude -- the most ignorant person in the room, but the deference our companions paid even Robinson's briefest comment was striking. For my part, I recall being struck by the unexpected sophistication -- even delicacy -- of his descriptive vocabulary, which was studded with phrases borrowed from the worlds of dance and music, mainly jazz, and framed with a kind of poetic precision.

Reading Wil Haygood's thoroughly marvelous new biography, "Sweet Thunder: The Life and Times of Sugar Ray Robinson," I was transported back to that memorable evening when I came across a phrase that that greatest of fighters had used to describe, in one of the films we watched, an almost imperceptible feint with head and shoulder that set up a winning combination of punches: "The best is always fragile."

With this book, Haygood -- a feature writer for the Washington Post -- completes a biographical trilogy that includes earlier prize-winning volumes on Sammy Davis Jr. and the Harlem congressman Adam Clayton Powell Jr., pivotal African American personalities whom the author clearly sees as having tilled the cultural furrows in which the seeds of the civil rights movement ultimately took root.

"Sweet Thunder" is by far the best of these books and, in describing an athlete now universally acknowledged as the greatest prizefighter who ever lived, better also than Robinson's own collaborative autobiography. Anyone who ever saw him in the ring, or has watched a film of one of his bouts, understands why boxing fans paradoxically insist on calling their sport "the sweet science." Because his professional record included multiple welter- and middleweight titles and a stunning overall record of 174-19-6, it's often unappreciated that Robinson was, along with Jesse Owens, the greatest amateur athlete of the 20th century. He won all 85 of his amateur fights, 69 by knockout, 40 in the first round.

Haygood gives a fine account of Robinson's career in the dazzlingly competitive welter- and middleweight ranks of his era, but where this lyrically written biography -- with its jazz-inflected prose -- truly excels is in its evocation of the culturally rich post-renaissance Harlem, where Robinson began boxing as a 9th-grade dropout. (He was born Walker Smith Jr. in Georgia in 1921; he borrowed the name Ray Robinson from a friend so he could take part in AAU competitions while underage.)

It was the culture of Harlem that actually educated, elevated and empowered Robinson, who became the first black fighter to negotiate his own contracts and manage his own affairs. As champion, he opened a popular jazz spot that was frequented not only by Caucasian friends, like Frank Sinatra, but also by other African American cultural giants with whom Robinson enjoyed close associations, including Lena Horne, Miles Davis and the poet Langston Hughes, who always regretted not being able to convince Robinson to appear in one of his stage pieces.

Together, in the postwar years, they came to epitomize what Haygood winningly calls "the Esquire style" -- icons of a personal cool based on that style magazine. "Above 125th Street, the periodical was being flipped open by jazz-playing hands, by young writers and dancers, by young pugilists. It advertised features on 'fiction, sports, humor, clothes, art, cartoons.' By the time that milieu had been mixed and soaked into the brew of uptown, a whole crop of men had emerged joining the well-heeled and their progeny to let them know that they too believed in the magic of art and style. Only these individuals felt compelled to add their own music. And so it was jazz that colored their Esquire-loving signature and came to flood the senses of the young Sugar Ray."

As strong as Haygood is on the active years of Robinson's career, his book is perhaps a trifle light on the formative early life (before he discovered boxing) and on the melancholy twilight that overtook him in Los Angeles when, after the money had run out and his dreams of a fresh start in film or television had come to nothing, he and his wife, Millie, were living in the upper half of a rented duplex on West Adams.

As Haygood writes, Robinson was inspired into social action during that period by a conversation with -- of all people -- Prince Philip when he and Millie were invited to Buckingham Palace to celebrate Queen Elizabeth's birthday in 1969. When the Robinsons returned to L.A., he devoted himself to raising money for and working directly with young people we'd now call "at-risk youth." It was a successful -- if always financially precarious -- program that taught its participants physical skills, self-confidence and tried to impart a touch of Sugar Ray's ineffable class. Florence Griffith Joyner, the three-time Olympic gold medalist and athletic style icon, was one of its graduates.

Nothing during that period, however, came close to the adulation Robinson received when he attended the weekly boxing cards at the old Olympic Auditorium. There always was something thrilling about the way Jimmy Lennon -- the incomparable announcer of so many memorable fights -- would save Sugar Ray for last during the traditional introduction of dignitaries that preceded each card: "And now," that faultless Irish tenor would intone, "I am calling to the ring, the former world welterweight champion, the five-time middleweight champion, pound for pound the greatest fighter in the history of the world, the champion's champion -- Sugar Raaaay Robinsooooooooon!" Into the ring Robinson would bound, Esquire dapper and light on his feet as a dancer, while the whole arena stood and cheered. No fight fan who ever was there would forget what they saw and heard.

Later, there would be years in the deepening shadows of what was called Alzheimer's and doubtless was the sort of pugilistic dementia a career of more than 200 fights makes almost inevitable. There was a sad and unseemly tug-of-war between his wife and children, all of which Haygood, perhaps wisely, passes over in silence.

As Sugar Ray, who died in 1989, said to his longtime coach, George Gainford, as he left the ring as a prizefighter for the last time, "No beefs, George. Sometimes, we got the best of it in the past."

timothy.rutten@latimes.com