IN the annals of literature Thomas Bowdler is undoubtedly best known for giving us the verb 'to bowdlerise', which means to take a book and cleanse it of everything that is deemed indelicate.

An English physician and philanthropist, Bowdler published in the early 1800s various editions of The Family Shakespeare, edited anonymously by his sister Henrietta, "in which nothing is added to the original text; but those words and expressions are omitted which cannot with propriety be read aloud in a family".

Among the alterations made by the hyper-sensitive Bowdlers was the omission in Hamlet of any suggestion that Ophelia may have committed suicide. Instead, her death was said to have been by "accidental drowning". In Macbeth, meanwhile, Lady Macbeth's heartfelt cry "Out, damned spot!" became "Out, crimson spot!". In another play, Henry IV, Part 2, the doxy Doll Tearsheet was removed from the cast list entirely, lest her lasciviousness lead little children to ask awkward questions.

Regrettable as these revisions may seem, they were greeted in some quarters with cheers. The poet Algernon Charles Swinburne was not alone in congratulating the Bowdlers for introducing young people to the works of the Bard. At least they did not seek to introduce their own words and ideas to the text as was often the case. Who can forget the Irish poet Nahum Tate who, in the seventeenth century, rewrote King Lear with a happy ending, which was how it was performed until the mid-nineteenth century?

Bowdlerisation, of course, is the first cousin of censorship, there not being terribly much to choose between the two. Their promoters are invariably do-gooders who think they know better and are determined to save us from our weak-willed selves. The latest member of this egregious crew is Mark Rylance, most recently to be seen playing Thomas Cromwell in Wolf Hall. Rylance, formerly artistic director of the Globe Theatre in London, has admitted that he censored Shakespeare's plays when adapting them for the stage.

"I have to make the decision, do I include that or not?" he said. "There are some very unfortunate things that characters say. If a character says it, it doesn't mean the author means it but since the Holocaust ... these statements have a lot more resonance now than they did at that time."

As statements go, this one figures high on the PC Richter scale. For a start, Rylance knows no more than I do, or, indeed, any scholar, what Shakespeare thought. Was he anti-Semitic? Possibly. Was he a racist, sexist, vegetarian? Who knows. Facts about him are few and generally of an unrevealing nature. What we really know of Shakespeare is what he wrote, or is supposed to have written. Whether he liked Jews or black people or women, we will never know. We can only surmise, and that is perilous.

What we do know, however, is that his plays were of their time and that, if we want to understand them, we must study that time and put what the characters in them say in context. Bowdlers and censors, of course, are rarely concerned with that. Their instinctive desire is to remove anything untoward, as we have seen recently in the case of Charlie Hebdo. But read things in isolation and the chances are you will come away with the opposite of what the author intended.

Take Shylock in The Merchant of Venice. To some readers he is the personification of the Jewish usurer, who is more concerned with protecting his ducats than his daughter and will always pursue his pound of flesh. But I have always thought him pitiable. "Hath not a Jew eyes?" Shakespeare has him say. "Hath not a Jew hands, organs, senses, affections, passions?"

Rylance's problem lies in his desire to foist present sensibilities onto the past. It is an ignorant way to proceed and panders to those who would cleanse culture of its right to shock. This year, for example, marks the 100th anniversary of the publication of John Buchan's yarn, The Thirty-Nine Steps, which contains much that may be deemed offensive, particularly to Jews. "The Jew is everywhere," he has the freelance spy Scudder utter, " ... with an eye like a rattlesnake."

Was this Buchan's own view? I would argue it was not. Hannay, the novel's hero, listens and reports and introduces a sceptical note, suggesting that he does not go along with Scudder's point of view. In other books, though, Hannay himself makes derogatory remarks about Jewish people which rather take one's breath away today. But that's surely the point. Literature is organic and must be read and reinterpreted by each generation, preferably in a form that is as true to the original as possible.