You almost certainly know this image featuring John Carlos. It's 1968 at the Mexico City Olympics and the medals are being hung round the necks of Tommie Smith (US, gold), Peter Norman (Australia, silver) and Carlos (US, bronze).
As The Star-Spangled Banner begins to play, Smith and Carlos, two black Americans wearing black gloves, raise their fists in the Black Power salute. It is a symbol of resistance and defiance, seared into 20th-century history, that Carlos feels he was put on Earth to perform.
''In life, there's the beginning and the end,'' he says. ''The beginning don't matter. The end don't matter. All that matters is what you do in between - whether you're prepared to do what it takes to make change.''
Raised by two involved, working parents, Carlos learnt to hustle with his friends in Harlem and fight his way out of and into trouble. When the police gave chase, he was often the only one who never got caught.
Running came so naturally, he never thought of it as a skill. As a teenager, he used to chase Malcolm X down the street after his speeches and fire questions at him. Carlos always knew he was good at sports and originally wanted to be an Olympic swimmer, until his father broke it to him that the training facilities he needed were in private clubs for whites and the wealthy.
That single moment on the podium cost Carlos dearly. More than four decades later, you'll find him at his desk in a spacious portable building behind the basketball courts at Palm Springs High School in California, where he works as a counsellor.
Bald, tall, with a grey goatee, Carlos, who turns 67 on June 5, is distinguished and convivial..
''The first thing I thought was 'the shackles have been broken','' Carlos says, casting his mind back to how he felt in that moment. ''And 'they won't ever be able to put shackles on John Carlos again'. Because what had been done couldn't be taken back.
''The greatest problem is we are afraid to offend our oppressors … I had a moral obligation to step up. Morality was a far greater force than the rules and regulations they had.''
The image certainly captures that sense of momentary rebellion. But what it cannot do is evoke the emotional turmoil and individual resolve that made it possible, or the collective, global gasp that came in response to its audacity.
In his book, The John Carlos Story, Carlos writes that his mind raced from the personal to the political and back again in the seconds between mounting the podium and the anthem playing. Among other things, he reflected on his father's pained explanation for why he couldn't become an Olympic swimmer, the segregation and consequent impoverishment of Harlem, the exhortations of Martin Luther King and Malcolm X to ''be true to yourself, even when it hurts''.
It was also a moment of silence. ''You could have heard a frog piss on cotton. There's something awful about hearing 50,000 people go silent, like being in the eye of a hurricane,'' he says.
And then came the storm. First boos. Then insults and worse. People throwing things and screaming racist abuse. ''Niggers need to go back to Africa'' and ''I can't believe this is how you niggers treat us after we let you run in our games''.
''The fire was all around me,'' Carlos says. The International Olympic Committee president ordered Smith and Carlos to be suspended from the US team and the Olympic village. Time magazine showed the Olympic logo with the words ''Angrier, Nastier, Uglier'' instead of ''Faster, Higher, Stronger''. The Los Angeles Times accused them of engaging in a ''Nazi-like salute''.
Beyond the establishment, the resonance of the image could not be overstated. The Black Power movement had provided a post-civil rights rallying cry and the anti-Vietnam War protests were gaining pace. Students throughout Europe, east and west, had been in revolt against war, tyranny and capitalism.
King had been assassinated and the US had been plunged into yet another year of race riots in its urban centres. Just a few months earlier, the Democratic Party's convention had been disrupted by violence between police and Vietnam War protesters. A few weeks before the Games, scores of students and activists had been gunned down by authorities in Mexico City.
The sight of two black athletes in open rebellion on the international stage sent a message to the US and the world. At home, this brazen disdain for the tropes of American patriotism - flag and anthem - shifted dissidence from the periphery of American life to prime time television.
Globally, it was understood as an act of solidarity with all those fighting for greater equality, justice and human rights.
Carlos remains politically engaged. Late last year he addressed Occupy Wall Street protesters in New York. ''It's the same fight as it was 43 years ago. We fought unemployment; for housing, education. It's the same thing as people are fighting for today,'' he says.
He defends the US President, Barack Obama, whom he believes has not been given a fair shake.
''If George W. Bush can have two terms to put this country into this mess, we should give Obama two to get us out of it,'' he says.
But today Carlos sees little hope of resistance emerging through sport.
''Today, if an athlete doesn't have a view of their history before them, then they have a view of just that big cheque in front of them,'' he says.
''It's not the responsibility of the oppressor to educate us. We have to educate ourselves and our own. That's the difference between Muhammad Ali and Michael Jordan. Muhammad Ali will never die. He used his skill to say something about the social ills of society.
''There will be someone else at some time who can do what Jordan could do. And then his name will just be pushed down in the mud. But they'll still be talking about Ali.''
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