Muhammad Ali was bigger than boxing and larger than life. He was a true icon of the 20th century who called himself “The Greatest” and backed up his words inside and out of the ring.

On Sunday, PBS airs part one of a sweeping new four-part documentary on the life and legacy of Ali. 

“We were interested in the entire story, a comprehensive biography from his birth and boyhood in Jim Crow segregated Louisville, Kentucky, to his death by Parkinson’s just five years ago,” said filmmaker Ken Burns, who co-directed the documentary “Muhammad Ali” with Sarah Burns and David McMahon. “And we treat the boxing — those matches are so dramatic — but also the spiritual journey of a questing and serious man about what his place in the world and in the universe was, and really see that he is intersecting with all of the themes of the last half of the 20th century: the role of sports in society, the role of a Black athlete, the definitions of Black masculinity and Black manhood, the changing dimensions and dynamics of the civil rights movement, race, faith, religion, Islam, war, politics, sex. All of those things intersect and what comes out the other side is just a compelling and unbelievable figure.”

Dealing with a multifaceted figure also stirs up a range of feelings.

“We often like to say he was loved at the end of his life but he was so divisive. I don’t think he was divisive, I think we [the public] were divisive,” Burns said. “We’re the ones who said to a Black man who was following his faith, ‘You’re giving the middle finger to the United States government. This is a political gesture.’ When in fact it was not that. So it’s a complicated story and Muhammad Ali is a very complicated person.”

Burns joins “Chicago Tonight” ahead of the documentary’s premiere, along with Donald Lassere of the Chicago History Museum, who for years was president and CEO of the Muhammad Ali Center in Louisville, Kentucky.

More: Watch our interview with Burns and Lassere on “Chicago Tonight: Black Voices.”