By Stan Wilson, CNN
(CNN) - As Muhammad Ali stood up and slowly raised his right hand to greet friends in celebration of his 70th birthday at the Muhammad Ali Center in Louisville, Kentucky, last weekend his voice was silent. But the three-time heavyweight champion winked, smiled and engaged with those who came to support him.
His 70th birthday on Tuesday represents a poignant milestone for a man once known for his speed, wit, grace and fearlessness.
“My father is feeling very blessed and proud to be turning 70,” Ali’s daughter, Hana Ali, said.
Fifty years ago, Ali proclaimed himself “The Greatest” and millions of boxing fans around the world agreed. His charisma and courage made him the most famous figure on the planet.
Ali’s legacy began in 1942, when he was born Cassius Marcellus Clay Jr. in Louisville, Kentucky, during an ugly era of racial segregation in America. At age 12, Ali's world changed forever when a white police officer introduced him to boxing. According to Ali biographer Howard Bingham, the young Clay had ridden his new bicycle to a carnival for free popcorn and candy. After discovering it missing, Clay vowed to beat up the thief. While reporting the theft, police officer and volunteer boxing coach Joe Martin persuaded Ali to learn to box. The sport became an outlet for his rage and offered the young fighter an opportunity to develop his remarkable talent.
Ali’s international fame emerged a few months after his 18th birthday, when he represented the United States at the 1960 Olympic Games in Rome and won a gold medal. While Ali returned to Louisville with a hero’s welcome, whites still refused to serve him because of Jim Crow laws and racial bigotry.
At 18, Ali turned pro and four years later, he stunned the boxing world by defeating a fighter most experts thought was invincible - heavyweight champion Sonny Liston.
The 1960s were glory days for Ali, but the civil rights era became a controversial and polarizing period in his life. He renounced his given name of Cassius Clay and joined the black separatist Nation of Islam.
“Ali was a child of the South and understood racial segregation, he watched as black people were beaten, bitten by dogs and lynched and all of that had an impact on him,” said Harry Edwards, a sports sociologist and University of California, Berkeley professor emeritus.
Outside the ring, Ali often found himself at the center of civil rights protests.
“Self determination was a powerful image at that time and instead of striving to share space with people who hated blacks, Ali took the position that “We as black men are able to stand on our own feet, develop our own institutions and be men,” Edwards said. “The slogan that 'I am black and I am proud' had a tremendous appeal to him and it had a generational change on the image and disposition of the black athlete."
In 1967, almost as quickly as Ali had arrived, his heavyweight title was gone - revoked after he claimed conscientious objector status and refused to serve in the Vietnam War. At the peak boxing age of 26, also Ali gave up tens of millions of dollars in endorsements and faced five years in prison, all in defiance of a war that he called “despicable and unjust.”
Ali would fight his case all the way to the U.S. Supreme court, where his conviction was overturned on a technicality in 1971.
“When Ali put everything he achieved on the line in deference to his religion and political principles that got attention around the world,” said Edwards. “People eventually came to believe Ali was sincere and over time there developed a tremendous degree of unquestioned integrity about him,” said Edwards.
On March 8, 1971, the world learned that even heroes have off days. Ali was barely back in the ring when his undefeated professional record came to an end. He lost to Joe Frazier in a 1971 match dubbed "The fight of the century." It was the first of three fights with "Smokin’ Joe.” In 1975, Ali faced Frazier a third time in the famous “Thrilla in Manila.” It ended with a 14th round knockout, a triumph by Ali.
Perhaps his greatest athletic comeback was in central Africa, where Ali knocked out the heavily favored young champion George Foreman in the fight known as the “Rumble in the Jungle.” In 1978, Ali would recapture the heavyweight title for a record third time, defeating Leon Spinks.
His last professional fight in 1981 marked the beginning of another battle, what Ali described as his toughest: the Parkinson's disease diagnosis he received three years later.
“My father’s spirit has experienced and survived many challenges,” said Hana Ali who co-authored his autobiography, “The Soul of a Butterfly: Reflections on Life’s Journey.”
After two decades of redefining the heavyweight division, Ali’s lifetime record: 56 victories, just five defeats.
According to Hana Ali, the heavyweight champion was never content with simply winning titles.
"I've always wanted to be more than just a boxer,” she quoted him as saying. “More than just the three-time heavyweight champion. I wanted to use my fame and this face that everyone knows so well, to help uplift and inspire people around the world. I've made my share of mistakes along the way but if I have changed even one life for the better, I haven't lived in vain,” quoting her father.
As his condition worsened, Ali continued to serve as a mediator in world conflicts. In 1990, before the first Gulf war, Ali personally visited former Iraqi leader Saddam Hussein to secure the release of 14 U.S. citizens held captive and used as human shields.
“The fact that he was a serious and dedicated Muslim devoted to put everything on the line including his life, in a culture like Iraq, if Ali comes in and says let these people go, even a monster such as Hussein could probably at some level be moved by his humanity,” historian Edwards said.
In 2005, Ali was presented with the Presidential Medal of Freedom, the nation's highest civilian honor. At the tribute on Saturday, American hikers Josh Fattal and Shane Bauer were invited to pay tribute and thank Ali for his role in persuading Ayatollah Sayyid Ali Khamenei, Iran's supreme leader, to release them from an Iranian prison.
“As a Muslim, my father’s spirituality is constantly growing,” Hana Ali said. “When he speaks about religion these days, my dad’s closing remark is always the same, 'There is only one true religion and that is the religion of the heart because we are all here to improve the human condition.'"
While Parkinson’s disease took its toll, Ali didn't retreat from public life. In a poignant moment in modern sports, Ali ignited the Olympic flame in 1996 to begin the summer games in Atlanta. With more than 3.5 billion viewers world-wide, the man once known as the most famous person on Earth slowly ascended the stadium steps, his hands trembling but never wavering - Ali at his best, again.
While Ali has been robbed of physical traits he once treasured - fluid, elegant moves - his commitment to human rights hasn't wavered.
“He was bigger than just the greatest boxer he was a transcendent iconic figure who impacted and influenced the character of a generation,” Edwards said.
As Ali turns 70, few would argue that Ali needed the crowds as much as they at one time needed him - not for personal approval, but because each saw the best of Ali’s humanity in themselves.
Hana Ali said: “My father said to me the other day, 'Belief in yourself is like a staircase, as long as we are here on earth we must continue to climb.’”
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