Apparently, it started with Ken Griffey Jr., centre fielder for the Cincinnati Reds, who made a request to change his number for a day. Not big news, except that the number he wanted was 42, and the day was April 15, 2007. On that date in 1947, a black man named Jackie Robinson sprinted out to play first base for the Brooklyn Dodgers. It was an epic moment in American life, a case where sport was ethically ahead of much of the rest of the society around it.

Why did the Dodgers do it? Enlightened self-interest? Maybe, but even if that’s all it was, that’s not all bad. But it still took courage and resolve for Dodgers’ General Manager Branch Rickey to take the step that his peers were not ready to try, though everyone with a baseball brain knew there were superb black players available. Several Dodgers threatened a boycott if Robinson were brought in. Rickey’s response went something like this: Fine. Sit out as long as you like. Good luck finding other work.

So yesterday, not just Griffey but a large number of players and coaches across Major League Baseball, including the entire squad of the (now) Los Angeles Dodgers, wore number 42. Presumably, no opponents spit on their cleats or urged them to “go back to the cotton fields!” I suppose that their teammates didn’t refuse to eat meals or even play catch with them. There were many shots in today’s news of groups of players, wearing number 42, with their arms around each other’s shoulders, as Brooklyn shortstop Pee Wee Reese famously did 60 years ago to quiet the leather-lunged bigots in Cincinnati, where they love the gifted Mr. Griffey now.

Many point out the irony that, sixty years on, the African-American is again becoming an endangered species in baseball. There are lots of reasons for that, many of which have nothing to do with racism. Baseball is no longer The National Pastime – football and basketball have surpassed it not only in attracting black athletes but in appealing to sporting audiences – but it was in 1947. And this story is about so much more than baseball. (For example, there is a great story here about an ordinary day at one of the many Jackie Robinson Memorial parks and stadiums across America. )

Robinson was a rather old rookie, 28. His career was brilliant – Rookie of the Year, six-time All-Star, Most Valuable Player in 1950 – but comparatively short. He entered the Majors – by the way, only a couple of months before another superb man and player, Larry Doby, broke the American League colour bar with the Cleveland Indians – after being a Southern California multi-sport star, serving in the American Army from 1942-44, and dazzling Montreal sports fans while playing for the minor-league Royals after the War. Among other things, he was once court-martialled for refusing — more than 10 years before Rosa Parks did — to go to the back of a military bus in Texas. His “insubordination” charge was overturned, though, and he was discharged from the Army with honour. He also remained prominent in the civil rights movement after his baseball career. With Jackie Robinson, it was always about more than baseball. (Baseball is about more than baseball.)

This is his epitaph: “A life is not important except in the impact it has on other lives.” Jackie Robinson is buried beneath, and ever exalted by, this inscription on his gravestone in Brooklyn.