A children's novel titled Captain Underpants does not, on first impression, sound like a contender for the most dangerous book in America.
Two young boys in the fourth grade of an American high school hypnotise their headmaster, Mr Benjamin Krupp, and transform him into the titular superhero, who wears his underwear without any trousers. Together they fight evil, which often materialises in the shape of their nemesis, Dr Diaper.
In other words, Captain Underpants provides the sort of good, mildly irreverent fun that young boys and girls lap up in the playground every day.
However, according to a report issued by the American Library Association's Office for Intellectual Freedom, Dav Pilkey's popular, long-running series inspired more complaints in 2012 than any other book in the US. The reasons given include: "offensive language" and "unsuited for age group".
In doing so, Captain Underpants beat stiff competition: The Kite Runner by Khaled Hosseini ("homosexuality, offensive language, religious viewpoint, sexually explicit"); Beloved by Nobel Prize winner Toni Morrison ("sexually explicit, religious viewpoint, violence"); and, it almost goes without saying, 50 Shades of Grey - although E.L. James' apparent transgressions ("offensive language, sexually explicit") are much the same reasons why the bonkbuster has sold millions around the world.
All of the above are in good company. Of Mice and Men, The Catcher in the Rye, The Color Purple and (for anti-family, occult/satanism, religious viewpoint, violence) Harry Potter are all regulars on the library association's top 10 most-challenged books. The list reminds us that censorship remains an issue in the 21st century, and that books still have the power to offend in a variety of ways.
These issues, and many more, are the focus of Banned Books Week which runs from today until Saturday. First launched in 1982, the week-long series of events promotes the freedom to read, while also keeping an eye on the forces that oppose this across the world.
Literary censorship has a long and ignoble history that goes hand in hand with writing itself. It pre-dates the origins of official state censorship in 443BC, when the Romans created the rank of "censor", in part to monitor the regimen morum: the guarding of public morals. China, by contrast, wouldn't create an official censor for another century.
Almost every nation has exercised legal censorship of literature in one form or another in the belief it is protecting its people's hearts and minds - whether this is Britain's "Chatterley Trial" in 1960 or John Cleland's Fanny Hill in Massachusetts in 1966, more than two centuries after the novel's publication.
Books have always proved particularly vulnerable to censorship of various kinds. Viewed in a positive light, this is because they offer a simple - but potent - imaginative threat to rulers of all kinds. Cheap and portable, easily shared and easily concealed, a book's compact form can hold and disseminate vast amounts of information, knowledge, news and wisdom - virtues that authoritarian leaders from Tsar Nicholas II to Chilean dictator Augusto Pinochet have wanted to eradicate as quickly as possible.
At the same time, their material form means they are easily destroyed by fire or water. Some of history's greatest cultural and intellectual tragedies may have been de facto acts of censorship. Historians have argued that at least some of the several fires that laid waste to the great library at Alexandria were started deliberately - although one book burning, ordered by the caliph of Baghdad, was not simply aimed at wreaking cultural havoc, but to provide fuel to heat the city's public baths.
In the centuries before Gutenberg's printing press enabled mass publication, destructive tactics such as this could literally remove a work - and not just a book - from the face of the planet. One of the most famous losses - the second book of Aristotle's Poetics - inspired Umberto Eco's The Name of the Rose. Eco's plot proposes that Aristotle's topic - comedy - so offended one fundamentalist Benedictine monk that he destroyed the world's only surviving copy.
In China, many seminal works were lost between 213BC and 210BC in what has become known as the "Burning of Books and Burying of Scholars". Seeking to unify the nation in a single mindset, Li Si, chancellor to the first emperor, Qin Shi Huangdi, ordered the eradication of many potentially important if subversive texts: the Hundred Schools of Thought, which challenged any attempt to impose a single vision of government on China, and also Confucius' compilation, Classic of Music, which has never been recovered.
More recently, fires started in Iraq's National Library after the fall of Saddam Hussein destroyed countless irreplaceable artefacts including an estimated 25 per cent of its 417,000 books, and 4,412 rare books and manuscripts. It was a near replay of the destruction of the House of Wisdom, an ancient library and centre for translation that was destroyed in the siege of Baghdad by Hulagu's invading Mongolians in 1258.
However, the most notorious example of mass literary destruction remains the Nazi bonfires that were ordered in April 1933 to rid Adolf Hitler's embryonic Third Reich of "un-German" books. Its capacity to chill is undiminished, not least as a prologue to the horrors of the Holocaust. The Säuberung ("cleansing by fire") lasted all summer, and concentrated on works by Jews, anarchists, communists, and opponents of Hitler's Social Democrats. The largest book-burning occurred in Berlin, when 40,000 witnessed Joseph Goebbels declare: "No to decadence and moral corruption! Yes to decency and morality in family and state! I consign to the flames the writings of Heinrich Mann, Ernst Gläser, Erich Kästner."
Other writers targeted by the Nazis included Bertolt Brecht, Albert Einstein, Sigmund Freud, Franz Kafka and Karl Marx. Foreign authors were also burned: Victor Hugo, Ernest Hemingway, D.H. Lawrence and Fyodor Dostoyevsky.
Such totalitarian intolerance inspired Ray Bradbury to write his science fiction classic, Fahrenheit 451 - the title inspired by the temperature at which paper burns.
Not all book censorship was so dramatic, visceral or public. Many authors have been their own censors, demanding that works, diaries and letters be burned, most often after their death. Philip Larkin instructed that his diaries be shredded, while Lord Byron's publisher, John Murray, burned the poet's memoirs a month after his death, convinced their content would cause a scandal.
Writers' intentions weren't always obeyed by their executors: Franz Kafka requested that his friend Max Brod consign all of his manuscripts to fire. Brod's refusal saved almost everything Kafka ever wrote. Virgil suffered the same fate with his epic poem The Aeneid.
Other seminal works needed legal intervention to be removed from bookstores. The reason, almost without exception, was sexual. Italy banned Hubert Selby Jnr's Last Exit to Brooklyn. France and Britain did the same to Vladimir Nabokov's Lolita. Canada and the US banned Henry Miller's Tropic of Cancer. James Joyce's Ulysses was effectively also banned in America after a chapter published in The Little Review was deemed obscene in 1921. Radclyffe Hall's classic The Well of Loneliness depicting a lesbian relationship was banned in Britain, despite containing only this sex scene: "and that night, they were not divided."
The most famous example remains the trial of Lawrence's Lady Chatterley's Lover in 1960. Despite the prosecution arguing that Lady Chatterley was not the kind of book "you would wish your wife or servants to read", the defence, aided by expert witnesses such as E.M. Forster, successfully established that the novel's explicitness was artistically justified.
Under the new Obscene Publications Act (1959), this was sufficient to override the earlier ban.
Much modern debate about literary censorship centres on China. Many established Chinese authors are routinely banned in their homeland: from Shen Congwen to Chan Koonchung, from Yan Lianke to Jung Chang.
The authorities seem equally unnerved by Zhou Weihui's overtly erotic Shanghai Baby as Ma Jian's coruscating depiction of the one-child law in The Dark Road. Nor is non-fiction any less threatening: despite being granted access to archives on the mainland, Frank Dikötter's prize-winning Mao's Great Famine has not been published anywhere other than Hong Kong.
How long this situation can be sustained is, like so much else on the mainland, open to fierce debate. With banned books legally available in Hong Kong, and pirate copies prevalent throughout the mainland, blanket censorship looks impossible in the long term.
Such openness might be aided by advances in file-sharing over the internet, and the comparative liberalism of President Xi Jinping.
Optimists might point to Tan Hecheng's Bloody Myth, a moving account of a government atrocity committed in Daoxian, Hunan, during the Cultural Revolution, which has been released after being banned for more than 25 years.
Then again, the Catholic Church's Index Librorum Prohibitorum (Index of Prohibited Books) lasted more than four centuries. So perhaps we shouldn't hold our breath.