Jackie Robinson knew from the start that his quest was bigger than baseball. Baseball was his vehicle -- proudly so. There are a handful of moments that define America's modern civil rights movement, and Robinson stepping onto a baseball field for the Brooklyn Dodgers on April 15, 1947, is among them.

That moment was a groundbreaking one for this country. Robinson broke baseball's color line, and from there, the United States would be changed forever. This Thursday would have been Jackie's 100th birthday, and will be the beginning of a year of celebration and remembrance by MLB to honor the man and the things he believed in.

His was a life lived with courage and dignity and purpose, and his presence on a previously all-white baseball diamond forced Americans to see the world in a way they'd never seen it before. If Jackie Robinson and Pee Wee Reese could be teammates and friends, if they could treat one another with respect and work together for a common goal, why can't the world change in other ways, too?

As Dr. Martin Luther King Jr. told Dodgers great Don Newcombe years later: "You'll never know how easy you and Jackie and [other baseball pioneers] Larry Doby and Roy Campanella made it for me to do my job by what you did on the baseball field."

So baseball will commemorate all of this and more beginning on Thursday with a series of events that will include widow Rachel Robinson and daughter Sharon and dozens of players and team executives, and will culminate in December with the opening of the Jackie Robinson Museum in New York City.

Commissioner Rob Manfred will join Rachel and Sharon as well as Jackie Robinson Foundation president Della Britton Baeza at the opening reception of the "In the Dugout with Jackie Robinson" exhibit at the Museum of the City of New York. On Thursday evening, MLB Network will air Ken Burns' biographical documentary, "Jackie Robinson."

Another highlight of the season will be Jackie Robinson Day on April 15, when all 30 teams mark the anniversary of Robinson's first game for the Dodgers in 1947. And in what has become an annual tradition, every player will wear uniform No. 42 -- Robinson's number, now retired across MLB. Individual teams are remembering Robinson's 100th birthday in a variety of ways during the season.

For instance, in July, the Braves are inviting teams from the Jackie Robinson Boys and Girls Club of Cairo, Ga. -- Jackie's birthplace -- to participate in their annual Youth Baseball Classic. In addition, the Jackie Robinson Foundation will have a traveling exhibit of museum items throughout the summer.

These efforts are aimed at telling Jackie Robinson's story and reminding us why he mattered. At times, Jackie Robinson has become more of an idea than a living, breathing human being, one who suffered almost incomprehensible cruelty to help change the world. He changed it for good, changed it with his strength and dignity, with his resolve and patience and fury.

"He didn't see baseball as the peak of his life," his widow, Rachel, once said. "He used baseball as a forum, used it for publicity, as a place where he could get his ideas across. He was in the forefront of thinking about black economic development, black political growth that was needed after the civil rights movement won the right to stay in hotels, ride the buses -- Jack was going to the next stage. That's what Jack was about."

Robinson wasn't a patient or passive man by nature. He played the game with an edge and wasn't inclined to look the other way on injustice, either. During his Army days, he was court martialed for refusing to move to the back of a bus.

As a player, he stayed in hotels so hot and dirty that he'd have to soak the sheets in ice water just to cool the room. Meanwhile, his white teammates were at the nicest place in town. He couldn't eat at their restaurants, either, and sometimes waited an hour on street corners for a cabbie inclined to stop for a black man.

He put up with it because he was proud and stubborn and because he knew how many people were counting on him. He loved baseball more than baseball loved him, and he wanted to show the world that a black man could succeed in the white man's league.

Only when he was secure as a ballplayer did he use a platform rarely afforded to black people to push for more change. Perhaps the real lesson of Jackie Robinson is about social responsibility. He was determined to leave the world better than he found it.

He attended rallies, fired off angry telegrams and lent his name to causes. There was a 1957 letter he penned to President Eisenhower on the subject of civil rights.

"I read your statement in the papers advising patience," Robinson wrote. "We are wondering to whom you are referring when you say we must be patient. It is easy for those who haven't felt the evils of a prejudicial society to urge it."

Hall of Famer Frank Robinson once said Jackie's debut with the Dodgers inspired him. Suddenly, there would be no man-made barrier. If he was good enough, he would have a chance.

"That's what drove me," he said.

Bob Watson played 19 seasons in the big leagues and served as general manager of both the Yankees and Astros. In the beginning, though, he was a scared kid from Southern California assigned to an Astros Minor League team in Salisbury, N.C.

One day, having been told he could not enter either the front or back door of a popular restaurant, he phoned home ready to quit.

"Now you have to understand, we were Dodger fans," Watson said. "My grandfather was a huge Dodger fan."

When Watson thought he'd had enough, he was reminded of Robinson.

"Jackie had it a whole lot worse than that," he was told. "If Jackie can do it, you can too."

Baseball has ushered Robinson into the consciousness of an entire new generation of people in recent years with its annual celebration of his life. Thanks to the ceremonies and speeches and community outreach work, countless players, fans, club executives and others know more about him than they might otherwise have known.

Robinson's family has continued to work on behalf of the things Jackie Robinson cared about, and that's part of what the next 12 months of celebration will be about.

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