WATCH: Ken Burns explains how America has always been a racist country

When considering major themes in American history, which he often covers, filmmaker Ken Burns put racism at the top of the list.

"I think the American question of freedom is a big one, the tension between individual freedom and collective freedom is a big one, but I think the sub-theme of American history is race," Burns told "Late Show" host Stephen Colbert.

"We were founded on the idea that all men were created equal, but oops—the guy who wrote that owned more than 100 human beings and didn’t see in his lifetime to free any one of them; didn’t see the contradiction or the hypocrisy. And so it set us on a journey where we are constantly having to struggle not with race, but racism."

According to the filmmaker, Trump taking two days to disavow the Ku Klux Klan is just one of many signs that racism still exists in America.

Burns’ new documentary is about Jackie Robinson, recipient of the inaugural MLB Rookie of the Year Award in 1947, an All-Star for six consecutive seasons from 1949 through 1954, and the winner of the National League Most Valuable Player Award in 1949. Robinson's legacy represents an end to the baseball color line—60 years of segregation in professional baseball.

“Jackie Robinson was the first African-American baseball player in the white major leagues,” Colbert told the audience, and whose legacy, like many historical figures, said Burns, is “smothered in mythology.”

“We thought it might be possible to liberate him from the barnacles of sentimentality that attach, because what Jackie Robinson has to teach us now is exactly the same as when he was alive,” Burns explained. “There’s nothing new under the sun. Human nature doesn’t change, it just randomly superimposes itself on the random chaos of events.”

Ken Burns’ Jackie Robinson documentary talks about Confederate flags, stop and frisk, the experience African Americans have driving, and thburning black churches—essentially Black Lives Matter.

“So, if we’re curious, but are not comfortable talking today, having a courageous conversation about race, let’s look at Jackie Robinson’s life and see how many of the same tropes that are part of our life today Jackie addresses. [He’s] not only the most important person in baseball, but the most important person in American sports.”

“And a great player,” added Colbert.

For the documentary, Ken Burns interviewed influencers ranging from Carl Erskine to the Obamas.

Watch: Ken Burns discusses Trump, Obama and Jackie Robinson on The Late Show.