The footage is simultaneously exhilarating and haunting.

In the rare recording we see a handsome, self-assured Muhammad Ali speaking to the Harvard University graduating class of 1975, where he had been invited to give the commencement address.

“I’m very flattered in coming here ‘cause you never could have made me believe years ago when I got out of high school with a D-minus average,” Ali said. “And they gave me the minus because I won the Olympics.”

Ali won the light heavyweight division gold medal in the 1960 Rome Games when he was still known as Cassius Clay.

When he addressed the Harvard graduates in ‘75, Ali was at the height of his popularity and was arguably one of most highly recognized faces in the world.

The Champ was 33 years old. Just eight months earlier, in October 1974, Ali had pulled off one of the greatest upsets in boxing history when he defeated the seemingly invincible 25-year-old champion George Foreman, in Zaire — the famous “Rumble in the Jungle.”

With the victory, Ali regained the world heavyweight boxing title that had been stripped from him in 1967. His title had been taken not by a boxer, but by boxing’s sanctioning commission in April 1967 after he refused to be inducted into the U.S. military.

In his 1975 talk at Harvard, Ali spoke about Uncle Toms and a condition of black brainwashing that he said kept blacks shackled.

“I don’t do no Uncle Tom-ing. I don’t do no shuffling,” he sad. “The Ali shuffle, but I don’t do the Tom shuffle.” The audience roared its approval as he then demonstrated the Ali shuffle.

Ali told the graduates he was baffled by the extent to which African-Americans in the civil rights movement went through such pains to desegregate, to push to go where they were unwanted. “Even before I was who I was,” he was baffled and angered as black demonstrators suffered physical abuse “marching, people pouring water on you, putting dogs on you. What in the hell is worth that? You got to be crazy, watching your sisters all beat up.”

He implored the black community to come back to itself, to embrace self-sufficiency. “We got the best food, the best music, everything else,” Ali said. There certainly were black Harvard graduates who appreciated the courage of those who risked life and limb to break down barriers to equal opportunity. But Ali’s underlying message of black brainwashing was on point.

He talked about the depiction of Jesus with blue eyes, of Tarzan as the white king of the jungle, beating up black Africans. He described white angels, white Miss America. “Everything good was white, the angel food cake was white, devil food cake was chocolate.”

As I watched the audience react to Ali, I wondered if the graduates, many of whom would become politicians, business magnates and leaders, heard what Ali was saying. I wonder how many today recognize how thoroughly that truth still resonates.

Ali won the world heavyweight title in 1964 when he knocked out the heavily favored Sonny Liston in the seventh round. Three years later, he was stripped of the crown after he refused on religious grounds to serve in the military, famously saying, “I ain’t got no quarrel with those Vietcong.”

This month marks the 51st anniversary of Ali’s conviction. He was sentenced to five years in prison (which he never served because his case was appealed). Ali received a fine of $10,000 and was also banned from boxing for three years.

Interestingly, two months before Ali’s address at Harvard, South Vietnam surrendered to North Vietnam. A month before the address, President Gerald Ford essentially declared an official end to the war.

Four months after the Harvard speech, Ali survived 14 punishing rounds of boxing to defeat Joe Frazier in Manila. Called the “Thrilla In Manila,” that fight arguably is one of the greatest in Ali’s career. There were more chapters to follow. Ali lost to Leon Spinks in 1978, and regained the title the same year by defeating Spinks.

Looking at the footage of Ali’s 1975 speech at Harvard now, we know his story would end with physical deterioration after years of absorbing punishment. Even in 1975, there were concerns about Ali’s health.

I interviewed Foreman at his Livermore, California, ranch a year after his 1974 fight with Ali and he expressed an awareness of, if not concern for, Ali’s long-term health. What struck me then and even now as I reflect on Foreman’s comments is how thoroughly Ali had gotten inside of Foreman’s head.

That defeat compelled Foreman to change his entire approach to boxing. Foreman realized that Ali had it right all along. The fight game, at its core, was entertainment. It was a game of charades. Years later, Foreman would reinvent himself as the lovable, cuddly, health-conscious Big George, inventor of the George Foreman grill.

When I look around my home and my office and see images of Ali, I realize I am as heavily invested in Ali as my father was in Joe Louis, the indomitable Brown Bomber.

And just like my father, I am just as unwilling to let emerging facts of Ali’s life diminish the impact he has had on my life, or on his heroism.

I have read multiple Ali biographies. My conclusion: Muhammad Ali was a human being, with all the flaws, frailties, contradictions and complexities that go along with being human.

He stood up to the U.S. government’s war machine and spoke for thousands in 1967 when he said, “Hell, no, I won’t go.” Many of those thousands were in the audience at Harvard. That’s why Ali was given a hero’s welcome, why he was celebrated in life and why he will be celebrated in death. He did not run and he did not hide.

Muhammad Ali was and is a true American hero.