In 1994, Home Box Office and Pepsico celebrated Black History Month by producing a poster that was intended to show black achievement: It featured a large picture of the pyramids and many smaller images, including one of the Sphinx. Worse, the companies sent 20,000 copies of the poster to predominantly black schools. Honest teachers in those schools had to explain why a corporate seal of approval had been given to a historical claim that just isn't true.

This "celebration" marked the high-water mark of Afrocentrism, a movement that had begun in the academy in the 1980s and gained astonishing momentum with the publication of Martin Bernal's "Black Athena: The Afroasiatic Roots of Classical Civilization" (1989). According to various Afrocentric books and popular assertions, ancient Egypt invaded ancient Greece, Plato and Herodotus somehow picked up their ideas in travels along the Nile, and Aristotle stole his philosophy from the library at Alexandria. Though the arguments were contradictory and scattered, the point was that Western civilization had been founded on materials and discoveries borrowed or stolen from black Egyptians.

During this whirlwind of dubious scholarship, the academic world mostly remained mum, hiding behind the curtain of academic freedom and withholding its criticism lest a statement of simple truth be branded "racist." For a 1991 column in U.S. News & World Report, I phoned seven Egyptologists and asked whether the ancient Egyptian population had been "black." Of course not, they all responded, but not for attribution, since, as one said, "this subject is just too hot."

The scholar who did the most to break this silence was Mary Lefkowitz, a mild-mannered classicist at Wellesley College. Without fully understanding the abuse she would invite by speaking out against Afrocentrism, she accepted an assignment in the fall of 1991 to write a long review of the second volume of Martin Bernal's "Black Athena" for the New Republic magazine. She was shocked to discover that the Bernal volume, and a stack of other nearly fact-free books on Afrocentrism, had made headway in the schools and even in the universities.

She concluded that the Afrocentric authors regarded history as a form of advocacy: Like other postmodernists, they believed that truth is impossible to know -- that all "narratives" are socially constructed and thus possess an equal claim to legitimacy. At the time, traditional scholarship was generally under assault, but the classics were particularly vulnerable, because they purported to study the foundational texts of the West. Attacking the classics as a complex system of lies was emotionally important to those who wanted to take Western culture down a peg. Feelings and politics mattered, not scholarship. As Ms. Lefkowitz puts it: "[Bernal] seemed to be saying that the most persuasive narrative was the one with the most desirable result. In effect, he was preaching a kind of affirmative action program for the rewriting of history."

"History Lesson" is Ms. Lefkowitz's personal account of what she experienced as a result of questioning the veracity of Afrocentrism and the motives of its advocates. She has advanced the intellectual case against Afrocentrism before, in "Not Out of Africa" (1997); here she takes a more personal approach, at one point mentioning the strain of the controversy as she battled breast cancer.

Outraged by the nonscholarly approach of Afrocentric writers, she somewhat naively imagined that facts would put their extreme theories to rest. She noted, for instance, that Socrates couldn't have been black, as alleged, because his parents were Athenian citizens and blacks, in classical Athens, were not eligible for citizenship. She noted, as well, that Aristotle would have had a tough time stealing his philosophy from the library at Alexandria, since he died before the library was built. Such arguments went nowhere, Ms. Lefkowitz writes, with those who saw Greek philosophy "as yet another case of a colonialist European plundering of Africa."

While Ms. Lefkowitz was being targeted by Afrocentrists nationally, she fell into a war on her own campus with Anthony Martin, a vituperative and litigious tenured professor of "Africana studies." It was an odd battle. Ms. Lefkowitz kept trying to make it a debate about evidence and truth. Mr. Martin made it personal and added a large helping of anti-Semitism. Eventually he turned out a book titled "The Jewish Onslaught," endorsed the crackpot theory that Jews had dominated the slave trade and demanded Jewish reparations to blacks.

When Mr. Martin sued Ms. Lefkowitz for libel -- claiming that she had misreported an incident involving him -- the dean of the college, Nancy Kolodny, declined to indemnify her. "It's your problem, she said to Ms. Lefkowitz. "The college can't help you." Some turned on Ms. Lefkowitz for dividing the campus. Others shrank from criticizing a black professor or were simply intimidated by the explosive Mr. Martin. Nan Keohane, Wellesley's president (soon to become the president of Duke University), offered little help. She urged one pro-Lefkowitz group to consider Mr. Martin's feelings and introduced an extreme Afrocentrist speaker as "a distinguished Egyptologist."

In the end, Wellesley behaved well. The history department refused to give credit toward a history major for courses in the Africana Studies Department, and Mr. Martin was denied a salary increase. The Anti-Defamation League found a law firm willing to defend Ms. Lefkowitz. After six years of legal wrangling, she won the case. Both Ms. Lefkowitz and Mr. Martin are now retired.

Though much of academia is still lost in postmodern theory and relativism, Ms. Lefkowitz insists on what we might call a counternarrative: Teachers owe it to themselves and their students to get as close as possible to the truth. The academy has still not firmly answered the central question of "History Lesson": What should the university do when a professor insists on teaching demonstrable untruths? No prattle about academic freedom, please.