Some of us were lucky enough to see James Brown convulse across a stage during his 73 years on Earth. Few of us were lucky enough to see him jump off a stage and into a swimming pool.

 At a 2006 concert in Tbilisi, Georgia, in the former Soviet Union — more than 6,000 miles from the Georgia that Brown called home — the “Godfather of Soul” performed at a swimming facility, the stage erected on the lip of an Olympic-style pool. During the crescendo of “Sex Machine,” Brown plunged into the chlorinated deep. Splash. Band members who dived in to fish him out were each paid a $200 bonus. Brown died on Christmas Day that year, a showman to the end.

The dive is one of many passages detailed in R.J. Smith’s “The One ,” a superb new biography of a tireless entertainer who spent decades tightening his grip on the boundless energy he radiated. While investigating the hardest-working man in showbiz, Smith breaks a sweat of his own. This is a meticulously researched book that tracks Brown’s childhood in the segregated South, his rise as a musical innovator, his tangled relationship with the Black Power movement, his connections to a handful of U.S. presidents and his golden years, tarnished by debts and drugs.

Like Brown’s music, Smith’s writing is both airtight and full of life, conversational and reflective. Brown once said that he came into this world silent, motionless and “stillborn” — resuscitated by an aunt who blew breath into his lungs. Smith seizes on this fantastic entrance: “One good thing about believing you were born dead is you come to feel nothing can kill you.”

He follows Brown through his youth in “the Terry,” the black neighborhood of Augusta, Ga., where the future superstar learned how to roll dice, strip cars, run with gangs and write words in his clothes with Clorox. Raised in his aunt’s brothel, Brown learned other things, too. At 22, he was a musician brimming with zeal. On stage he flipped, strutted, mounted pianos and landed in splits. He crawled across a barbershop floor while his band auditioned for a new manager. Bobby Byrd, the founder of Brown’s first group, the Famous Flames, remembers telling the young singer to take it easy: “We’d say ‘What’s wrong with you? By the time it’s time for us to try and make a record, you’ll be done killed yourself.’ ”

‘The One: The Life and Music of James Brown.’ By R.J. Smith (Gotham. 455 pp. $27.50) (Gotham Books)

Brown, of course, never took it easy. But at pivotal moments in Brown’s career, Smith slows down to describe the music and the magic it transmitted. When Brown infuses what becomes an iconic performance with ear-jolting screams, he’s “throwing ugly all over the Apollo.” During his performance on the “T.A.M.I. Show,” the legendary 1964 concert film that introduced Brown’s electricity to the masses, the singer is “conducting the band from the depth of his paroxysm.”

In the ’70s, those paroxysms were felt globally. Brown influenced Afro-beat originator Fela Kuti and Ethiopian great Alemayehu Eshete. In Washington, Chuck Brown was so inspired by James Brown’s signature funk dialect that he invented his own and called it go-go. To hip-hop pioneer Afrika Bambaataa, James Brown’s music became a strand of DNA. But as Brown’s influence surged, his career started to sputter. Disco, a genre that vexed so many artists, stymied Brown, too. Before long, he was running from creditors and battling a PCP problem.

Smith quotes him sparingly throughout the book, as if doggedly chasing after this tornado of a man. He knows Brown’s incredible story is best told by the people, the music and the zeitgeist that surrounded him — and what was left in his wake. As pop, R&B, hip-hop and dance music continue to explode into different shapes online, Brown’s fingerprints are still traceable. But we’re waiting for a performer who can walk onstage and make the same kind of splash.

Richards is pop music critic for The Post.

The one

The Life and Music of James Brown

By R.J. Smith

Gotham. 455 pp. $27.50