Back in 1968, when a callow 22-year-old named Donald J Trump was busy building a business empire and not walls, two American athletes, Tommie Smith and John Carlos, stood on the podium at the Olympic Games in Mexico City.
Heads bowed, each had one black-glove encased fist raised in the air in a shock symbol of their protest against racial prejudice in their United States homeland.
It was the most significant political gesture in sport after the refusal of the world heavyweight boxing champion, Muhammad Ali, to accept the military draft to fight in Vietnam the year before.
It was labelled the Black Power salute. But this was a total misnomer. It was about black equality.
Naturally sprinters Smith and Carlos outraged the fuming authoritarian American President of the International Olympic Committee, Avery Brundage, and were dispatched home to be vilified and ostracised. They were sporting pariahs for years until it was finally acknowledged - as with Ali - that they were simply making an extremely relevant point which had done much to validate the civil rights movement.
Fast forward to 2017 and we now have the 70-year-old Trump installed as the President of the United States and making "Slavery Avery" seem like Che Guevara with his hysterical reaction to the latest and largest political protest by US sports stars.
The personal stand, or rather kneeling down, last season during the US anthem by Colin Kaepernick, a mixed-race player who publicly protested against racial injustice and the police killings of unarmed young black Americans, now has been extended to much of the National Football League (NFL).
Racial discrimination and those police shootings is a noxious situation which Trump, a supposedly passionate sports fan and one-time boxing promoter, has done little, if anything, to diffuse.
Indeed, his typically incendiary comments have put him not only at verbal war with North Korea but with sport in his own nation.
Speaking at a Republican rally on Friday (September 22), Trump described those who knelt as "sons of bitches" who should be sacked by team owners.
Adopting his theatrical posturing from his days as as TV host of the US version of The Apprentice, he demanded they should be "fired".
What he actually said was: "Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'get that son of a bitch off the field right now. He is fired. Fired'.
"Total disrespect of our heritage, a total disrespect of everything that we stand for."
Abraham Lincoln, George Washington, Franklin D and Theodore Roosevelt, Harry S Truman, John F Kennedy - great American Presidents of the past - must be turning in their proverbial graves every time this man opens his big mouth.
Trump's comments drew applause from the crowds in Alabama - well, they would there, wouldn't they?
It is understandable that a predominantly red-necked rabble would salivate at such wretched rhetoric.
The Associated Press has observed that more than 200 players around the NFL knelt or sat during the National Anthem on Sunday (September 24).
The highest total was in Washington before the nationally televised night game, where nearly the entire Oakland Raiders team protested, in addition to six Redskins. No-one sat or knelt at the Pittsburgh at Chicago game, although the Steelers stayed in the tunnel. In Tennessee, both the Titans and Seattle Seahawks remained inside through the anthem.
More than 20 players and staff from the Baltimore Ravens and the Jacksonville Jaguars - not all of them black - took the knee, as they say, or linked arms before their match at Wembley Stadium in London.
NFL commissioner Roger Goodell praised the players, saying he was proud to see their defiance. He said that Trump's comments "demonstrate an unfortunate lack of respect for the NFL, our great game and a failure to understand the overwhelming force for good our clubs and players represent in our communities".
It is not just the NFL. LeBron James, currently America's best known basketball player, has declared on Twitter that Trump is "a bum" and accused him of "using sports as a platform to try and divide us when the purpose of sport is that it brings us together".
Baseball has also been swept up into the controversy with Bruce Maxwell, a catcher for the Oakland Athletics, dropping to one knee during the national anthem to register his own protest.
Over this issue, as well as many others, the current President of the US is showing himself at best a bullying buffoon and at worst an unmitigated bigot.
Trump said yesterday his previous comments had "nothing to do with race" but were about "respect for our country, flag and national anthem".
Ah yes, the national anthem.
Is it not about time national anthems were dumped from sport anyway?
I have long been an advocate of doing so. All they seem to do is create even more unwelcome jingoism, notably at the Olympics.
What is wrong with simply raising the medallists' national flags and playing the Olympic Anthem, which at least is somewhat more melodious than some of the dirges we have to endure - including ours in Britain which I have not been inspired to sing since I was a schoolboy?
Perhaps this is an argument for another day.
Meantime, we are witnessing once again that sport and politics are inextricably entwined.
"Sport has the power to change the world," Nelson Mandela once said.
"It has the power to inspire. It has the power to unite people in a way that little else does.
"It speaks to youth in a language they understand. Sport can create hope where once there was only despair. It is more powerful than Government in breaking down racial barriers."
We wonder what Mandela would have made of Trump. Or vice-versa.
No doubt Trump would have shaken the great man's hand when actually he should have been made to kneel before him.