Jackie Robinson trotted out to play first base for the Brooklyn Dodgers on April 15, 1947, and what was that someone said about the journey of a thousand miles beginning with a single step?

Then and there, the modern civil rights movement began in America, which is why Wednesday we celebrate the 73rd anniversary of baseball's finest hour. That's also why Robinson's No. 42 was retired forever in 1997 and why his story of courage and sacrifice is told across the land.

• Complete guide to 2020 Jackie Robinson Day

Jackie Robinson could not have understood that he would start a movement that would stretch from a bus in Montgomery, Ala., to a lunch counter in Greensboro, N.C., to a bridge in Selma, Ala. All he knew for sure was that he had right on his side and that he could not fail. Had he failed -- and failure in this instance could have taken a multitude of shapes -- the quest for racial fairness would have been more difficult.

"[He] represented both the dream and the fear of equal opportunity," Robert Lipsyte and Pete Levine wrote in "Idols of the Game." "It would change forever the complexion of the game and the attitudes of Americans."

To see a black man playing baseball with white players forced Americans to see the world in a way they'd never seen it before. With that little nudge, change began.

One year later, President Truman integrated the military (1948), and then came an avalanche: Brown vs. Board of Education outlawed the segregation of public schools in '54, and President Johnson signed the Civil Rights Act in '64.

All that followed that day 73 years ago -- the integration of Little Rock Central in 1957, Ole Miss in '62 and the University of Alabama in '63 -- can be traced to a spark ignited by Jack Roosevelt Robinson and the Dodgers.

Sure, those things may have happened even if Jackie hadn't played an inning for the Dodgers, or if he'd fallen on his face. But because he succeeded -- because he was both a very good player and a good teammate and a leader, because he won the respect of virtually all his teammates, including some who adamantly opposed the idea of blacks and whites together -- other barriers didn't seem quite so insurmountable.

Best of all, Jackie Robinson seems more alive than ever. Once virtually assigned to the dustbin of history as a nearly forgotten figure in grainy black-and-white video, Major League Baseball has made sure every player, owner and fan understands why No. 42 is on display in every ballpark.

In the last decade, Robinson has gotten the Ken Burns treatment in a wonderful PBS documentary, and also been the subject of a Hollywood blockbuster, "42," starring Chadwick Boseman.

Robinson is suddenly more than an idea or an ideal. He's a living, breathing man who was subjected to almost incomprehensible cruelty. He lived with death threats and hate mail, pitchers throwing at his head and legs, catchers spitting on his shoes and an endless string of taunts and curses from opposing dugouts and fans.

While his white teammates stayed at the best hotels on the road, Robinson was sent to places that reeked of filth, places so uninhabitable he would soak his bedsheets in water to get a measure of relief from the sweltering nights.

Dodgers executive Branch Rickey pleaded with Robinson not to retaliate to any of the indignities. If he did, he'd be the one judged, and harshly.

This was the ultimate ask for a player as competitive as Jackie Robinson, a player who played the game fast and angry. Or as a white teammate once told him, "Jackie, they don't all hate you because you're black. Some of them hate you because of the way you play."

As "Boys of Summer" author Roger Kahn wrote: "Robinson could hit and bunt and steal and run. He had intimidation skills, and he burned with a dark fire. He wanted passionately to win. He bore the burden of a pioneer, and the weight made him stronger."

After his retirement in 1956, Robinson used his platform to push for change, especially in lobbying baseball to give a black man a shot to manage a Major League team.

That's what he spoke about in his last public appearance shortly before his death in 1972. When Frank Robinson was hired to manage the Indians in '75, he spoke of Jackie.

"I thank the Lord that Jackie Robinson was the man he was in that position," Robinson said. "The one wish I could have is that Jackie Robinson could be here today to see this happen."

When the Dodgers unveiled a Jackie Robinson sculpture in 2017 -- the first statue of any kind at Dodger Stadium -- its design was taken from Robinson's steal of home against the Yankees in the 1955 World Series.

"I thought [stealing home] captured Jackie Robinson's significance in American history," sculptor Branly Cadet said at the unveiling. "It takes courage and focus and timing to steal home. Similarly, those qualities were required of anyone breaking the color line. The day he stepped on that baseball field was an important day, not just in baseball, but in American history. We wanted to honor that."

Capturing the moment in time struck Robinson's family as appropriate because it reflected his attitude.

"That's what he brought to Major League Baseball," his daughter, Sharon, said.

Around the base of the 700-pound bronze display is embedded some of Robinson's most memorable quotes, including one that's a favorite of Rachel Robinson, Jackie's widow:

"A life is not important except in the impact it has on other lives."