Famously, the writings of neither Charles Darwin nor Adolf Hitler appeared on it. The works of at least one saint – the Polish nun St Faustina Kowalska – did. In 1966, the Index Librorum Prohibitorum of the Roman Catholic church ceased after 407 years to have the sanction of ecclesiatical law. However, in 1985, the head of the successor body to the Holy Office in Rome - which kept and updated the church's register of banned books - made clear that "the Index retains its moral force despite its dissolution". That same enforcer, then Cardinal Joseph Ratzinger, is this country's guest today. Perhaps the presence among us of a Pope so identified with the control of heresy – through a 24-year stint as Prefect of the Congregation of the Doctrine of the Faith – should concentrate our minds on censorship.
Almost everyone – secular or religious, radical or conservative – believes in censorship at least some of the time. So debates about banning and proscription always turn on substance and degree. Next week, a project devised by London Libraries – with partners across the country – will give us a chance to sharpen our perceptions and clarify our ideas. The "Banned Books" reader promotion will present 50 titles that for one reason or another have fallen foul of official censorship.
Its forbidden list includes some of the most illustrious of subversive classics, from the Origin of Species itself to Orwell's Animal Farm. It also picks several modern causes célèbres: Rushdie's The Satanic Verses, Nabokov's Lolita, Easton Ellis's American Psycho, and Lawrence's Lady Chatterley's Lover.
The event will highlight some bizarre interdictions. Mark Twain's Huckleberry Finn has fallen victim to heresy-hunting on both left and right. Dan Brown's The Da Vinci Code incurred the censor's anger in the Middle East. The Harry Potter novels have stirred the wrath of pious American librarians for allegedly "satanic" sympathies.
Frankly, this selection errs too much on the cosy side. Many of the weirder prohibitions will reinforce a glib sense of superiority towards redneck Bible-bashers, small-town prudes and Stalinist apparatchiks. Other controversial books would pose far sharper questions to a liberal culture. So I have chosen ten works - none in "Banned Books" - that might stir a tougher discussion of the costs, and benefits, of truly free expression. I don't think any should be banned, but should public libraries stock them? If so, which?
1/ Sherry Jones, The Jewel of Medina. Criminal violence prevented a UK edition of this novel about the Prophet's wife Aisha, after an attack on its publisher's home.
2/ David Britton, Lord Horror. Cleared of obscenity in 1992, Britton's sulphurous blend of Holocaust themes and SM porn made Savoy Books in Manchester the most prosecuted publisher in Britain.
3/ Osama bin Laden, Messages to the World. Expertly edited by Bruce Lawrence, this collection of the al-Qa'eda leader's statements will not be gracing any display shelf soon.
4/ "Richard E Howard" (ie Richard Verrall), Did Six Million Really Die? This Holocaust-denial pamphlet by a National Front stalwart still sways neo-Nazi minds.
5/ Richard Lynn, The Global Bell Curve. The psychologist advocates the central role of inherited racial differences in intelligence, putting East Asians at the top and sub- Saharan Africans near the bottom of an ethnic IQ scale .
6/ Marquis de Sade, The 120 Days of Sodom. For some the magnum opus of the "divine marquis", his industrial-scale porn epic comes (in a recent edition) prefaced with de Beauvoir's essay, "Must we burn Sade?". No, the great feminist said.
7/ Pauline Réage, Story of O. The most notable novel by a woman in the Sadeian tradition, in all its icy masochistic poise. The author's real name was Anne Declos.
8/ AM Homes, The End of Alice. As much a reversed-out Lovely Bones as a homage to Lolita, Amy Homes's fictional journey into the paedophile mind prompted calls for its banning from the NSPCC.
9/ Sayed Qutb, Milestones. In this core text for jihadis, the Egyptian ideologist fashioned a still-influential manifesto for every later generation of angry, militant Islamists.
10/ Adolf Hitler, Mein Kampf. We know too much about the message, but what about the royalties? A Jewish charity sent back cash received from them; does the state of Bavaria still hold the rights?
A Gallic bow to queens of crime
Obituaries of Claude Chabrol have drawn attention to the quintessential Frenchness in the great director's dissection of guilt-ridden bourgeois life. Up to a point... In fact, two fine Chabrol films took the form of adaptations of novels by an Essex girl: Ruth Rendell. La Cérémonie (1995) came from A Judgement in Stone; La Demoiselle d'honneur (2004) from The Bridesmaid. Perhaps suburban secrets and quiet hatreds know no borders. But the female English mystery-writer has a curious cachet in French cinema - as anyone who relished Charlotte Rampling's icy turn as a Queen of Crime in François Ozon's film Swimming Pool will know. Thank, or blame, Dame Agatha for that.
Free words in the autumn air
Next Friday's discussion between Daniel Pennac and Quentin Blake at the Free Word centre in London forms part of Flow: the Free Word Festival. Now in its second year, the festival runs from this week until 5 October. As in last autumn's inaugural programme, there's a strong international flavour. On 5 October, the enigmatic Albanian master Ismail Kadare - surely a Nobel laureate one of these years - will be in conversation with Julian Evans. Storyteller Seema Anand will introduce four Punjabi writers - Amarjit Chandan, Manjinder Virk, Shazea Quraishi and Shamshad Khan - on 20 September. And on 30 September, a dedicated Translation Day will include a seminar on promoting foreign literature (in which I will be taking part), a discussion of translated children's books with Axel (Gruffalo) Scheffler, and a presentation of the new – and extremely welcome – Harvill Secker Young Translators' Prize. Find complete festival details at www.freewordonline.com.