It was a sweltering Bermuda afternoon in August 1965. The average person, local and visitor alike, felt as drained of energy as a dead car battery. But then Muhammad Ali was not the least bit average.

Crowned the world heavyweight boxing champion less than a year earlier, the charismatic 23-year-old American had no sooner set foot in Bermuda for the first time than he was engaging in some characteristically flamboyant theatrics and firing off quicksilver verbal flourishes.

Mobbed at the foot of the aircraft steps by a scrum of American reporters who had flown here to cover his exhibition bout at the Bermuda Tennis Stadium, he was asked what his future plans were. Ali immediately galvanised the tired and perspiring journalistic assemblage with a headline-grabbing offer, throwing down the gauntlet to the most serious contender for his crown.

He offered a title challenge to two-times former champ Floyd Patterson and the news was flashed around the world from the Bermuda airport tarmac.

“Yep, Patterson’s my man,” he said. “But if he whips me, I’m going to want an hour with him later in private.”

In the event there was no need for any post-fight fisticuffs. What was by then one of boxing’s most highly anticipated grudge matches went ahead on November 22, 1965.

Ali won by a technical knockout in the twelfth round after dominating the bout throughout. It was also the night some old ways of thinking about Ali and race in both sport and broader American life were laid out flat.

Friction had been building between the two men for months. Ali had publicly labelled Patterson an “Uncle Tom”, in part because he refused to call him Muhammad Ali, the name he had adopted the previous year after joining the Nation of Islam.

Patterson did indeed routinely refer to his Kentucky-born rival by his birth name, Cassius Clay — “What’s my name?” Ali later famously taunted him during their bout. He had also openly questioned the wisdom of his Kentucky-born rival’s affiliation with the sometimes controversial black nationalist sect and second-guessed the extent of Ali’s actual knowledge about the civil rights struggle.

Patterson seemed to suggest the “Gaseous Cassius” and “Mr Swellhead Bigmouth Poet” nicknames he had earned for showboating boasts about his athletic prowess ever since his gold medal-winning performance at the 1960 Rome Olympics were equally applicable to his fledgeling political activism.

In many ways the bout Ali announced in Bermuda was to be a classic old bull-young bull confrontation. It was a metaphor for that moment in the black American experience and, to some degree, the black Bermudian experience as well, one played out in that most challenging of arenas, boxing’s square ring.

This was the immediate post-John F. Kennedy period, the optimism and sense of possibility that had permeated that administration snuffed out along with the young president’s life on a Dallas street. Black patience with the gradualist approach to reform championed by Martin Luther King Jr, the National Association for the Advancement of Coloured People and other traditional civil rights groups was eroding in some quarters, giving way to new forms of resistance and vehicles for empowerment.

If Ali was emblematic of the revolutionary new black consciousness of the 1960s, Patterson, just seven years his senior, was a throwback to the early years of the struggle with its emphasis on incrementalism and evolutionary change.

An intimate of Dr King and a courtier at JFK’s Camelot, “Patterson was ... the artist,” said Norman Mailer, describing the former champion’s natural gentility. “He was the man who could not forgive himself if he gave less than his best chance for perfection” and he expected the same punctilious, old-school modus operandi from others.

He was also the man soon to destined to be obscured by Ali’s enormous shadow and his entirely more robust approach to fighting both opponents in the ring as well as the uglier manifestations of racial and social injustice that he encountered. When it came to those vexed subjects, his mind proved to be every bit as nimble as his dancing footwork; and Ali’s thoughts and words connected with the power of his hammer-blow jabs.

It had been that way since 1955, when, as a 12-year-old, he had glimpsed photographs of a lynched black Southern teenager in Life magazine. His aversion to racism had been almost instinctive ever since then. Perhaps not coincidentally, he had started to learn to box that same year, nominally to avenge the theft of a treasured bicycle — almost certainly, at some deeper level, to symbolically avenge himself on an unjust society.

“I used to be Cassius Clay,” the champ told the Bermuda magazine Fame during his 1965 visit. “You hear people talk about ex-presidents, ex-convicts, anything of the past. That is why I am ex-Cassius Clay and now Muhammad Ali — in Arabic, ‘One worthy of praise’.”

He went on to explain to veteran Bermudian journalist Charles Webbe that Floyd Patterson and other more conservative-minded elements, both black and white, had misread him, underscoring that his desire to see black empowerment in no way diminished his interest in more universal humanitarian concerns.

“People think I’m crazy,” he said. “I’m not crazy. I’m a new symbol of the upcoming black man. Anybody black is going to have a hard time in this world. A black man must have race pride or he is lost ... Identification is of more value than gold.”

History has proved him correct.

He was both an emblem of his era and one of the individuals who shaped it as a sportsman, showman, activist and cultural icon, as a symbol of black pride and resistance and, above all, as an exemplar of personal courage.

Individual action and personal transformation are often cited as being key to wider social and cultural changes. And Ali was a continuous work in progress in both areas between 1964 and his 1981 retirement, a blurred figure always in motion, always fighting his corner in and out of the ring, and never very far from the popular consciousness throughout this period.

To borrow a line from Robert F. Kennedy, another one of that era’s most inspiring and transformational figures: “It is from numberless diverse acts of [individual] courage and belief that human history is shaped. Each time a man stands up for an ideal, or acts to improve the lot of others, or strikes out against injustice, he sends forth a tiny ripple of hope, and crossing each other from a million different centres of energy and daring those ripples build a current which can sweep down the mightiest walls of oppression and resistance ...”

Ali was just such a man, holding true to his beliefs despite threats of imprisonment and a near career-ending banishment from boxing prompted by his refusal to be inducted into the Vietnam-era US military on religious grounds.

He demonstrated this same unwavering commitment to principle throughout his life and brought resolute determination, physical artistry, mental vigour, wit, grace, excellent judgment and raw power to bear on opponents both inside the ring and outside of it. Ultimately, this combination of physical strength and indomitable strength of purpose helped him to contend for so long with his most formidable foe, the Parkinson’s disease that afflicted him for during his final decades.

“I don’t mind if people make a mistake and call me Cassius Clay,” he told Charles Webbe while in Bermuda in 1965. “It’s going to take them a while to get used to it. Soon they will get accustomed to calling me Muhammad Ali, ‘one worthy of praise’.”

He was right. Within a few years the whole world had grown not so much accustomed as acculturated to his name and feats. Ali, by then the most famous and most instantly recognisable individual on the planet, never wanted for praise for the rest of his long and extraordinary life.

Muhammad Ali was one of God’s most remarkable one-off prototypes, too complexly and lovingly crafted to ever go into mass production. He was unique. He was irreplaceable. He was, in fact, the greatest.