A conversation with his daughters helped spark the African journey that Harvard Prof. Henry Louis Gates Jr. takes readers on in his new book.

"So, Daddy, what in the world am I supposed to have in common with them?" Gates's youngest daughter, Liza, asked seven years ago during a train ride through Zimbabwe with her dad, who had taken his children on the trip to help them connect with their African roots.

"Nothing," his older daughter replied. "They live in mud huts, they are covered with dust, their clothes are ragged. . . . They don't even wear shoes."

That scene opens "Wonders of the African World," the recently released companion book to the acclaimed PBS series that aired last month. Like the documentary, the book chronicles Gates's travels through 12 countries four years after that conversation with his daughters. The journey exposes the ancient civilizations of Africa--a side of the continent we rarely ever see.

Prince Georgians will get to hear about that journey tonight when Gates discusses the book at 7 p.m. at the Oxon Hill branch of the public library, 6200 Oxon Hill Rd.

Gates, chairman of the Department of Afro-American Studies and director of the Du Bois Institute for Afro-American Research at Harvard University, also will talk about another book, "Africana: The Encyclopedia of the African and African American Experience," which has hit the market about the same time.

A 2,100-page volume, this one-of-a-kind encyclopedia includes contributions from 400 writers and covers the culture and history of Africa and its descendants across the world.

The book, co-authored by Harvard's Kwame Anthony Appiah, includes an exhaustive array of black history events, debates, controversies and significant people from every discipline--religion, politics, academia, sports, culture, literature, the arts and sciences. A multimedia version was released on CD-ROM this year.

The books are pricey--about $89.95 in most places for the encyclopedia and $40 for "Wonders." But Vertigo Books, which arranged the book signings with the county's library system, will sell both for 20 percent off at tonight's event, which is free. The encyclopedia also includes a $10 rebate coupon.

Gates writes that he was first intrigued by Africa in 1960 when, as a 10-year-old, he decided on his own to memorize the names of all African countries that became independent that year and their new leaders. Later, as an undergraduate student at Yale University, he spent six months in Tanzania, where he worked at a mission hospital and explored from coast to coast.

Gates returned to Africa many times after that, eventually taking his daughters, no doubt hoping they, too, would bond with the motherland.

I can appreciate the girls' honesty and confusion.

Few of us associate grandeur and sophistication with the Africa we have come to know through the media, myths and warped history passed down for generations, sometimes in our own families.

"Let's face it squarely," Gates writes. "When most of us think of Africa, the images that come to mind are of poverty, flies, famine, war, disease and limitless acres of savanna inhabited only by majestic game."

I was amused when I read Gates's description of his father receiving the "I ain't left nuthin' in Africa" award each year at their family reunion. That same award could go to my own dad, a lovable black man who seems genuinely baffled by my fascination with Africa.

In a poignant opening chapter, Gates explores the ambivalence many African Americans feel toward the ancestors who sold their own into slavery. As he travels into Ghana and Benin, he doesn't shy away from the role Africans played in the slave trade.

But he takes us, too, to Axum in Ethiopia, where the practice of Christianity is believed to be older than in any Western European country and the Lost Ark of the Covenant is said to be housed. We go to Timbuktu, once a mighty center of academics and learning unmatched by universities emerging in Europe, and to East Africa, where the mystique of Swahili is unraveled.

Gates closes in South Africa and Zimbabwe, where he explores the lost cities and surviving art and architecture of the Shona people.

That chapter helped me reflect on my own trip to South Africa in 1994 to cover the election of Nelson Mandela as that country's first black president. There just three weeks, I saw mostly the ugly side of an African nation struggling to free itself from the grip of apartheid: the worst poverty I had ever seen, widespread unemployment, illiterate men and women denied an adequate education by an oppressive white government.

Gates's book shows another, more glorious side.

I lingered, too, in the early part of the book, where Gates uncovers the royal history of the Nubians, who produced the black Pharaohs of Egypt's 25th dynasty. From the Sudan across the Egyptian border to Aswan, Gates showcases the ancient ruins--tombs, temples and burial grounds--of Nubia.

He writes about the mixed feelings he felt when he saw the government-sanctioned Aswan High Dam. The dam, which has improved the Egyptian economy, created a 125-mile lake that washed away many Nubian villages and much of their history.

My husband and I felt the same sense of sadness and loss as we saw the dam first-hand during a 10-day trip to Egypt in August. But like Gates, we were impressed by the warmth of a resilient people who looked so much like us that a couple of times men assumed my husband was Nubian and approached him in the native language.

This is the Africa that Gates introduces in his book. It is important, he says, that all people get to know this unknown side.

"All human civilization wears Africa on its face, just as surely as my daughters and I do, as their children's children will, as do we all," he writes. "And until the West--and the rest of us--knows Africa, we can never truly know ourselves."

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CAPTION: Henry Louis Gates Jr., of Harvard University.

CAPTION: "Wonders of the African World" by Henry Louis Gates Jr. is the recently released companion book to the acclaimed PBS series that aired last month.