The runaway success of Miguel de Cervantes's "Don Quixote" when it was first published in 1605 was a relief to the author, whose other works had languished. His chronicle of the adventures of a delusional knight--who mistakes windmills for giants and inns for enchanted castles--and his loyal squire, Sancho Panza, became a best seller, with six editions rolling from the press in its first year. But the book never turned a profit for Cervantes, who died destitute a year after publishing its sequel in 1615.

Too bad Cervantes isn't around to collect now. To celebrate the 400th anniversary of "Don Quixote," to which no one owns the rights, 10 publishing houses have printed new editions, flooding stores around the world with fresh copies. One version, compiled by the Royal Spanish Academy and sold by Alfaguara for a modest 9.50 euro, has sold 600,000 copies in Spain and Latin America over the past two months. "We expected to sell about a million copies throughout the year," said Alfaguara spokeswoman Angeles Aguilera. "But we actually ran out around Christmas. It's great to have Cervantes on the best-seller list after 400 years."

For publishers, literary anniversaries are almost as profitable as being chosen for Oprah's Book Club. According to Eurydice Montrobert, communications director of FNAC, one of France's biggest bookstore chains, sales tend to triple in an anniversary year. Last year saw the centenary of "Bloomsday" on June 16, the single day on which the events of James Joyce's "Ulysses" take place. A high-profile marketing campaign by Joyce's publishers pegged to the date helped double sales of the Penguin Classics edition. In France, publisher Poche sells 25,000 of Colette's sensual novels in an average year; during the 50th anniversary of her death last year, Poche moved 60,000. And the 200th anniversary of George Sand's birth last year more than doubled demand for her rustic novels. Poche sold 50,000 copies compared to 18,000 in 2003.

Tourist boards are also figuring out how to cash in on the commemorations. In Spain, the regional government of Castilla-La Mancha, where many of Don Quixote's adventures took place, has created a public company to organize about 2,000 performances, exhibitions, concerts, films and plays--including "Don Quixote: The Shadow of the Knight," which runs at the Palacio del Infantado of Guadalajara until May. Nantes, the birthplace of French science-fiction pioneer Jules Verne, who died a century ago, is wooing tourists with exhibits, plays, concerts, films and conferences. In September the city will reopen the lavishly restored Jules Verne Museum. And the Bronte Parsonage Museum in Yorkshire, in northern England, is hoping to attract fans with readings, film screenings and an exhibit of manuscripts, letters, photos and other memorabilia commemorating 150 years since Charlotte Bronte's death.

Critics argue that concocting events and reissuing special editions to lure readers detract from an author's accomplishments. "It portrays a terrible lack of confidence, as if you can only draw attention to someone if they happen to have a birthday rather than because they're worth reading," says Boyd Tonkin, literary editor of The Independent. Blasting the barrage of histories that have come out preceding this October's bicentennial of the battle of Trafalgar and Admiral Nelson's death, Tonkin wrote that publishers should concentrate on finding new material rather than on mining the celebrity calendar. "Our whole cultural economy is based around manufactured events," he says. "Publishers should be led instead by a stronger sense of what they think is important."

For some, marking the passage of time can be thought-provoking in itself. Anniversaries highlight how perceptions of an author have changed over the years and can trigger a reassessment of their work. "D.H. Lawrence: The Life of an Outsider"-- a new biography by John Worthen published on March 2, the 75th anniversary of the author's death--uses unpublished letters from Lawrence's wife, Frieda Wakeley, to cast fresh light on the writer's turbulent life and his motivations for writing "Lady Chatterley's Lover." "We've gone through different ways of thinking about Lawrence, dismissing him for being shocking, then for his 'purple prose'," says Laura Barber,editorial director of Penguin Classics. "Then there was a feminist backlash. It's only now, with this biography--which is very clearsighted--that we can assess how radical he was in terms of English literature and how he changed society."

Anniversaries can also give marginalized authors another chance in the limelight. First published in 1857, "Wonderful Adventures of Mrs. Seacole in Many Lands," the insightful autobiography of a Jamaican nurse who met with racism and rejection from Florence Nightingale's "Angel Band" during the Crimean War, never received the attention it deserved. "She's not as well known as Florence Nightingale but her story's just as amazing, and so an anniversary like this is very useful," says Barber, who is releasing a new edition this week, 200 years after Seacole's birth. Such celebrations can also help broaden an author's readership. Leading Irish poet Patrick Kavanagh's "Selected Poems" has always sold well since it's widely studied in Irish schools. But during last year's commemoration of his centenary, bookstores sold three times as many copies of a pricier new hardback edition, "Collected Poems," as the school text typically sells in a year.

In some cases, savvy publishers are linking new works not to the anniversaries themselves but to other jazzy events connected to the narratives. Although a bold relaunch of Penguin's Shakespeare series coincides with the bard's 441th birthday in April, the publishers are promoting it in conjunction with a new production of "Henry IV" at London's National Theatre. The new books have blurbs on the back that outline the plays--they aren't assuming readers know the stories--and no notes within the text to make them more accessible. "We're learning from how film and theater market [the plays]," Barber says. "We want to remind people the play isn't just one director's interpretation and that they really do come to life on the page as well as the stage. Go see a play or a film, then dust down the text and remember how amazing the language is." After all, marking the passage of time is the heart of narrative, and great storytellers manipulate it skillfully. If advertisers and publishers do the same, birthdays and death dates can be more than commercial stunts. To write them all off would be tilting at windmills.