Ask a teenager to expound on Homer and the answer may have less to do with ancient Greek poetry than with the blundering nuclear power plant worker from the animated TV series "The Simpsons."

But make no mistake, say classicists including James Dixon III of Grove City College, the earlier Homer -- the literary one -- is still important.

Epics such as the "Iliad" and the "Odyssey" -- even if they sometimes seem as remote as a chariot in the digital age -- are critical underpinnings of Western civilization that one must not miss.

"If you want to be a well-read person, you need to understand the grand traditions of literature," said Dr. Dixon, who chairs the school's English department. "These are cultural treasures. They have made us who we are."

Just as passionate about what well-educated Americans should read is P.K. Weston, who taught in the South before coming to Point Park University. Among her must-reads is a more recent novel by Ralph Ellison, "Invisible Man," which describes a black man's search for his identity in 20th-century America.

The book and its contemporaries "give us a clear view of the human condition," said Dr. Weston, an English professor who heads Point Park's honors program. "They place our humanity in a larger context."

So, which of these campus scholars speaks the greater truth about being well-read? Who is more capable of creating a top-notch book list for you or for your child? The answer could be neither.

That's because debates about essential reading are almost always open-ended and sometimes fairly heated. In fact, scholars in this country have spent more than a quarter century arguing over expansion of the Western Canon, that compendium of works by generally white and dead male authors that has dominated classroom curricula for generations.

"There is no literary Grail," said Ben Slote, an associate professor of English at Allegheny College. "There is an issue of cultural literacy, or what it takes to be part of mainstream America. But exactly what that means is up for grabs."

Some will eagerly suggest the Bible as essential literature given its insights into Judeo-Christian traditions. Others say reading the Constitution and Bill of Rights is critical to functioning in a democracy. Still others might point to "The Vagina Monologues," a popular but controversial collection of women's attitudes toward their bodies.

To be sure, there are plenty of informed reading lists, from Harvard Classics and assorted university curriculum programs to The College Board's "101 Great Books," a grouping geared to college-bound readers. Locally, the Carnegie Library of Pittsburgh has lists by age group.

Many of the most celebrated of these compilations have common threads that have changed little over time, said Don Wentworth, senior staff librarian in the Carnegie's reference department. They are populated with names like Shakespeare, Whitman, Dickens and -- yes -- Homer among many others.

What has happened in recent decades is that those lists have been expanded to include such authors as Mr. Ellison, Toni Morrison and Alice Walker, additions that reflect cultural changes including the civil rights and women's movements, Mr. Wentworth said.

Still, the built-in problem with any list, no matter its length, is all the worthy titles that are left off, said Loriene Roy, a professor at the University of Texas at Austin and president of the American Library Association.

And long-standing placement on a list is no guarantee that an author's writing is still commonly required in the classroom, or even recognizable to the average person on the street.

"There are a lot of reading lists out there. Is anybody reading them? That's another ballgame," Mr. Wentworth said.

Literary awards, and even strong book sales, have never guaranteed universal acceptance.

J.K. Rowlings' Harry Potter books, which deal with boyhood sorcery and magic, are a runaway hit. But they also top the American Library Association list of works this decade most often subjected to efforts to have them removed from circulation.

Over the decades, "Catcher in the Rye" and "To Kill a Mocking Bird" became literary classics, but they were flash points, too.

"They are among the most banned books of all time," Mr. Wentworth said.

The question of what's appropriate to read starts early on as parents try out their first Dr. Seuss book on their children and gently bounce them up and down to the rhythm of nursery rhymes during baby lap-sits.

"We tell parents the important thing is to start reading to their children from the beginning, so they hear words and hear language," said librarian Patte Kelley, head of the Carnegie Library children's department.

Infants gradually learn that pages are turned from right to left, she said. Nursery rhymes such as Mother Goose stick in a child's mind the way advertising jingles do and become building blocks for vocabulary.

Experts say exposing a child to a variety of subjects is important.

Dr. Roy suggests that children "learn about the culture that's near and dear to them and also something about other cultures." But just as important, she said, is helping children develop the habit of reading simply for fun.

She cites her own 17-year-old son. He's read "The Great Gatsby" and "The Scarlet Letter," had six years of Latin and tackled the "Iliad." But for pleasure, he's also read "A Confederacy of Dunces," a 1980 comic novel and modern cult classic about an eccentric college graduate whose foray into the job market includes hot dog vending and work in a pants factory.

Of course, the world won't end if a child skips some books on a reading list. But bypassing classic stories or nursery rhymes can mean missing out on a shared cultural experience.

"If someone said 'That's a Cinderella story' and you have no idea who Cinderella is, then you would be lost," Ms. Kelley said.

In the same way, some books geared to older audiences are so frequently referenced in society that people ought to be familiar with the concept, regardless of whether they actually read the work.

Consider "Big Brother" from George Orwell's book "1984" about fictional totalitarian states, or the predicament of an aviator in Joseph Heller's "Catch 22" whose effort to avoid dangerous missions by claiming insanity is stymied by a rule stating that flying such missions willingly proves insanity, but seeking to avoid them means one's sane and therefore obliged to keep flying.

Dr. Slote said Mr. Heller's piece of fiction is among the most important books of the last century.

"The book basically captured something that arose in the 20th century that touched all of our lives -- the absurdity of bureaucratic rules," he said. "In fact, its title has become a phrase of currency even among those who have not read the novel."

And when deciding what to read, let's not forget the need to have something to say at the water cooler.

Books that remain on best-seller lists for months, from "Freakonomics" with its unorthodox application of economic theory, to "The Devil in the White City," a work about an architect and a serial killer, become a sort of required reading of their own.

"As social beings we want to read what other people are reading," Mr. Wentworth said. "And what made a best seller in the '40s and '50s is distinctly different from what makes a best seller today."

Still, why do some books endure, even as others fade? Why is "The Scarlet Letter" still required in the classroom, and why is Shakespeare a must read?

Call it the great truth "delivered in an extraordinary package," said Dr. Weston. "It's the ability to take the same words that you and I have and do something truly remarkable with them."

"I don't know how many times I've read 'Moby Dick,' " she said. "I swear, every time I read it, I find more."

Of course, when it comes to colorful verbiage, there's no telling what will get a crack at immortality. Consider another widely read book, the Oxford English Dictionary, whose authors in 2001 felt they had no choice but to expand the language with this new word -- "Doh!" -- meant to describe frustration.

The source of that exclamation? None other than TVs' Homer Simpson.