It took five years to sell out the first printing of 2,000 copies. For students told to read it, "it can be a tough sell," one scholar says. And any number of readers, angry with the author's perceived preachiness, toss the book away half-read.

And yet "Walden," by Henry David Thoreau, is a universally acknowledged classic of American literature with yearly sales that most American authors today would bleed for.

"Walden," celebrating its sesquicentennial this month, is doing just fine. Indeed, it is a far bigger bookstore blockbuster today than when it was first published Aug. 9, 1854.

For every one of those readers who scorn the book, it seems, there are countless others who regard it as the great guide to a life lived well, if not a virtual bible.

"Walden," of course, is Thoreau's iconoclastic account of his 26 months living beside Walden Pond in Concord, Mass., beginning in July 1845, in a small cabin he built himself, a mile from any neighbor.

In scholarly circles, the "Walden" sesquicentennial has been an event for months. The Thoreau Society during July built its annual meeting in Concord around the book, including a tag-team public reading of the entire text. Many bookstores and libraries around the country are holding special readings or "Walden"-related events.

In the pantheon of American literature, "Walden" competes with enduring titans such as "Moby-Dick" or "Leaves of Grass." But, outdoing many other classics, "Walden" has been translated into scores of foreign languages -- and, in its many editions, is thought to sell in the six figures every year.

It doesn't hurt that "Walden" is chockablock with catchy quotes that show up on calendars and chapter headings all the time, all the better to keep its embers aglow. For example:

"The mass of men live lives of quiet desperation."

"Beware of all enterprises that require new clothes."

"Simplicity, Simplicity, Simplicity."

"If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away."

You've seen them.

But "Walden" is much more. Its deepest appeal, scholars say, is its insistence that the reader ponder his or her life and ask whether it is the life the reader actually wants to live.

" 'Walden' is a book that challenges us to think about how we live our lives," said Joel Myerson, distinguished professor emeritus at the University of South Carolina. "And it is a book that challenges us at any time or any generation because the questions are as relevant today as they were 150 years ago."

What is life about anyway? "Is it to accumulate money, or is it to accumulate a more inner spiritual wealth? These and many other questions are what Thoreau addresses," Myerson said.

Thoreau loved paradox and used it well to raise those questions. In "Walden," for example, when writing of train travel, he says "the swiftest traveler is he that goes afoot." The reader then learns that Thoreau has added up the hours of work it takes to pay the fare to a village 30 miles away and determined that he could walk there in less time without ever having done a lick of work.

The point is not that the reader shouldn't take the train but rather that the reader ought to consider whether that train trip, and what it takes to make that train trip, is in keeping with what matters in life.

"I don't think he would have refused to fly on a plane and all the things you hear people say," said Sandra H. Petrulionis, associate professor of English at Pennsylvania State University and a Thoreau authority. "But he would have forced us to examine the basis of those choices. How do we live simply in a world that has become so complicated [that] most of us don't have time to sit down and have dinner with our families five nights a week? What kind of cars do we drive? How much money do we need, versus how much we want?"

Petrulionis said some students find Thoreau arrogant or aggravating but concede that he makes them think. "You are not supposed to be happy when you read this," she said of "Walden." "You are supposed to be darned uncomfortable."

"Walden" took off slowly. When the first printing finally sold out in 1859, the book went out of print.

"If you were reading a newspaper in 1854, you would never have pegged this book as lasting more than six months," Myerson said.

But it returned to print in 1862, and, according to Houghton Mifflin, the successor firm to Thoreau's original publisher, Ticknor and Fields, the book has not been out of print since.

In fact, it is hard to keep track of how many editions in English are on the market at any given time, some in paperback, some in hardcover, some annotated, some illustrated, some inexpensive, some precious. Several new editions appeared just this year. And then there are all the foreign editions.

" 'Walden' is arguably the most translated work of American literature in terms of the number of editions in foreign languages and the number of languages in which it has been translated," Myerson said. "The Thoreau Society collections have literally hundreds of foreign-language editions of Thoreau's writings."

At the society's annual meeting last month, scholars from abroad arrived with, and donated to the society, an additional two dozen or more new foreign-language editions, Myerson said. One Japanese scholar said there were 13 Japanese translations of "Walden."

Elizabeth Hall Witherell of Northern Illinois University, editor in chief of "The Writings of Henry David Thoreau," a multivolume scholarly series published by Princeton University Press, said the "Walden" edition in that series sells about 6,000 copies a year, and she estimates some 75 other editions are available.

Part of its universal appeal, perhaps, is that "Walden" can be read on many levels. It can be read as the account of an extended experience in nature, or it can be read as satire on 19th-century life, and both of those readings are supported by the text.

But it is as philosophy, as one of the great self-help books, as a spiritual message, that is "Walden" at its most powerful.

"He asks you not to be happy with the way things are. That is always very unsettling and disturbing," said Wes Mott, a professor of English at Worcester Polytechnic Institute.

"It is a radical book in the most fundamental sense," Mott said, "not because it tells you [you] must do this or you must not do that, but because it asks you to balance out these competing forces to have a whole life."

Walden Pond in Concord, Mass., was Thoreau's only neighbor for 26 months. His account of the experience marks its sesquicentennial this summer.