A few years ago, in an interview with the documentary filmmaker Ken Burns about Theodore Roosevelt, I said on camera that Roosevelt liked to kill wild animals, that he was, as I perhaps inauspiciously put it, a killer.

When you leave a Ken Burns interview you have no idea what you said will wind up in the film, if anything. Nor do you have any control over the final product, which is an expression of Burns’ genius. Although I stand by my statement, which I believe any rational human being would agree with, a few people of the Theodore Roosevelt establishment were outraged by what I had said. Let’s just say I have a pretty heavy price for telling the truth as I know it.

A week ago, I was in Walpole, N.H., to be interviewed by Burns for his forthcoming documentary film on Benjamin Franklin. You can have no idea how hard I worked to get ready for the interview. I know a fair amount about Franklin, but I have never before tried to master Franklin’s life, memorize his best quotations or think synthetically about his life and achievement.

In the weeks leading up to my trip to Walpole, I read five or six Franklin biographies, looked up every connection of Franklin to Thomas Jefferson and to John Adams and wrote out more than 150 pages of all caps notes on virtually every aspect of his life.

Not to get ahead of myself, but the interview went very well indeed, and I believe at least one of my short statements will appear in the film. On the other hand, everything I said could easily wind up on the cutting room floor.

But that is not the point I wish to make. When I read the biographies, I took special interest in the last weeks of Franklin’s life in the spring of 1790 because our man Jefferson, just back from France, stopped to visit Franklin on his deathbed on his way to New York to take up his duties as America’s first secretary of state. I found what I needed about that last meeting — it is very moving historical moment — but what I learned not only greatly increased my already high estimation of Benjamin Franklin but reduced my respect for Mr. Jefferson.

Franklin was born in 1706. He was 84 when he died on April 17, 1790. One month before he died, Franklin sent a petition to the new American Congress urging it to do something sooner rather than later about ending the institution of slavery. Nothing came of the petition, but in response, a Georgia representative by the name of James Jackson delivered a vicious denunciation of the anti-slavery position on the floor of Congress. He argued that slavery was a positive good. He argued that black Africans were better off on Christian plantations in America than in their native continent. He argued that if we freed black slaves, we’d have to live with them as free fellow citizens and no respectable person could want that.

Benjamin Franklin, at death’s door, responded by writing the last of his many outstanding parodies. He invented a speech — recently discovered — from 100 years previously by one Sidi Muhemet Ibraim of Algiers. The Islamic leader had been petitioned to release Christian sailors who had been kidnapped by Islamic pirates and were now being used as slaves in the North African Islamic states.

Franklin, who was a genius at turning the mirror, simply put all of Congressman Jackson’s arguments into the mouth of Sidi Muhemet:

• That Christian sailors were better off in the enlightened world of North African Islam than they would be if they were released.
• That the sacred scripture endorsed the kidnapping, enslavement, and forced conversation of infidels from the West.
• That if the Christian slaves were released, many of them would choose to stay in north Africa and no respectable Muslim could accept that. Etc.

It was one of Franklin’s most brilliant satires, worthy of Jonathan Swift. As with most “flip the lens” experiments, Franklin was able to point out the hypocrisies of the pro-slavery lobby in American life.

In the current crisis, just turn the lens:

• If Barack Obama had paid off a porn star.
• If Barack Obama had invited Pakistan to investigate Jeb Bush.
• If Barack Obama had declared that John McCain was not a true hero.

You get the point.

Franklin’s anti-slavery satire didn’t change much, but it alters my view of Franklin, who in virtually his last breath attended to the great crime, the great original sin, of the American experiment. He could not let himself die without addressing this fundamental paradox of American life, this stain on such pronouncements as Jefferson’s “All men are created equal and are endowed by their creator with certain inalienable rights.” What will you speak out about in your last hours of life? What are the issues that nag at you, that keep you up at night, that you know we need to address, that you understand as fundamental to the future of our national experiment?

So, let’s review. At the end of his life, George Washington determined to free his slaves, not immediately, but after the death of his wife, Martha. When she died in May 1802, 137 Mount Vernon slaves were freed. The president of the United States at the time was Thomas Jefferson, owner of more than 200 slaves at any given time. Of Washington’s gesture we may think “too little too late,” or “pretty convenient to do the right thing when you would no longer benefit from an abominable injustice you were quite willing to live with through your whole life.”

But the plain truth is that Washington did the right thing, as we understand the right, and Benjamin Franklin, living on borrowed time, used some of his accumulated prestige and moral capital to urge the Congress of the United States to debate the end of slavery.

But what did Thomas Jefferson do at the end of his life?

The answer is nothing. He freed a handful of slaves at the time of his death in 1826, all members of the Hemings family. The rest of his slaves were soon sold at auction — families split up, some individuals sold to faraway slaveowners they had never met.

You can say that Jefferson didn’t actually own his slaves by 1826, so he wasn’t really in a position to do anything meaningful about an institution he knew was a crime against human right. Fair enough, but of course we know Jefferson lived so far beyond his means all of his adult life that he put himself into the position of having mortgaged his slaves to outside creditors. Insolvency isn’t something that just happened to Jefferson, like a hailstorm two weeks before harvest. It was the result of a life of profligate spending on home improvements, books, scientific instruments, wine and a wide range of gimcracks.

What shall we conclude?

In my opinion, there is no conclusion but this: At some point fairly early on, Jefferson learned to live with slavery and the fact that he was one of the more significant slaveholders in the United States, the only one who had written “all men are created equal.”

So, I expressed my disillusionment with Jefferson as I sat 3 feet across from the great and charismatic Burns, and I said it with the passion of deep disappointment. It was the most powerful statement I have ever made about Jefferson and slavery. It came about because of new reading I have been doing at an advanced age. We must never stop reading and expanding and raising our consciousness.

It was Benjamin Franklin’s final act of moral courage, when he was operating on a very thin fund of vitality, that made me turn my attention back to Jefferson, searching for parallels, and what I saw was complacency and self-interest, not moral courage.

I don’t know if what I said will get into Burns’ film. Probably not, but who knows. I do know this. If my statement winds up in his documentary, I know I will not be chastised by the Jefferson establishment because they are not touchy, not protective of their hero and not determined to celebrate rather than evaluate one of the most important figures in American history.

Jefferson said it best. Of the University of Virginia, he wrote, “this institution will be based on the illimitable freedom of the human mind. for here we are not afraid to follow truth wherever it may lead, nor to tolerate any error …”