‘For Sale a sober honest, and healthy Negro Girl of twenty one years, well acquainted with country work, and having fourteen years to serve. To prevent unnecessary trouble, the price is 150 dollars.” William Duer placed that ad in 1814, just a few years before he became president of Columbia College, now Columbia University. The notice is flagged in a new report from Columbia about the school’s long and extensive ties with slavery.

Columbia now joins Brown, Harvard, Georgetown and plenty of other elite institutions in uncovering this checkered past. “I do believe any institution has to face its truth,” Columbia President Lee Bollinger said last year when the project launched. “It’s always shocking when you look back and realize things we think of as deeply immoral were taken for granted as a part of life.”

A number of schools have not only come clean about their bad actions in the past, they’ve also tried to make amends. For instance, after Georgetown learned its founding Jesuits profited from the sale of 272 slaves, it announced with much fanfare it would offer their descendants preferred treatment in admissions.

Universities, especially their faculties, will come away from all of these revelations with a renewed sense of their “privilege.” They’ll beat their collective breasts about America’s and their own original sin. But what they won’t take away is the one thing that academia could truly use right about now — some humility.

The question is this: Why, when there were plenty of abolitionists around, did your school just go along with the business of slavery? Why weren’t your professors challenging the prevailing wisdom of society’s upper echelons? Why weren’t faculty at least engaged in arguing about this brutal institution?

Perhaps these academics weren’t progressive the way our academics are today. They didn’t realize — like modern “woke” folk — that they were supposed to be on the cutting edge of social change.

But cutting-edge academia hasn’t always worked out so well, either: Progressive academics were among the main supporters of the eugenics movement of the late 19th and early 20th centuries.

At the time, right-thinking people assumed that “science” had the solutions to the problems of the day.

Founders of the Museum of Natural History, academics like Harvard biologist Charles Davenport and philanthropic leaders from the Rockefeller Foundation and the Carnegie Institution all believed people’s intelligence and their worth as human beings were inextricably tied to their race.

The result was mass sterilization in America well into the 20th century. A new PBS documentary called “The State of Eugenics” documents how 7,600 poor whites and blacks were sterilized in North Carolina alone. At least 30 other states also had such federally funded programs.

And where were our university leaders? In 1912, Harvard President Charles William Eliot told the Harvard Club of San Francisco that “Each nation should keep its stock pure. There should be no blending of races.” Eliot even served as vice president of the First International Eugenics Congress. Many academics agreed.

It’s no coincidence that Columbia professor Franz Boas was one of the lone critics of eugenics. As a German Jewish immigrant, Boas experienced discrimination in his field of anthropology. But his status as an outsider also probably gave him a better perspective on the academic debates of the day.

But where will the next Franz Boas come from — the next academic willing to fight the majority of his colleagues? After all, the views of university professors have, if anything, become more uniform in recent years — and perhaps dangerously so.

It’s not just that academics claim consensus on issues such as manmade global warming. It’s not even their unflagging belief that the government is in the best position to determine how capital is allocated in our economy.

No: Modern academia also seems certain that gender is a “social construct” — and that surgically altering our bodies so they resemble those of the opposite sex is a good idea. A new survey, meanwhile, shows that less than a quarter of Americans think people should be able to legally change their sex. And while Americans have long been evenly divided on the question of abortion, one survey showed that 99 percent of Ivy League professors want no restrictions on abortion at all.

Diversity of opinion has been curtailed on campus so much that professors — even those with total job security — don’t want to rock the boat by disagreeing with the campus orthodoxy.

Maybe we’ll look back some day and conclude that we permanently disfigured thousands of young people in a misguided effort to “treat” a psychological disorder. Maybe we’ll see that abortion really was a moral outrage on par with slavery or forced sterilization.

Today’s intellectual elites have no interest in questioning such practices, let alone stopping them. But don’t worry: They can say they’re sorry later.