My novel features an early 19th century bookseller who sells obscene books, and this surprised me. I come from a liberal family but a sexually modest one. What was I doing with a character who roamed the early American countryside, hawking risqué literature from the back of his carriage, including what would become the most banned book in U.S. history, Fanny Hill, Memoirs of a Woman of Pleasure?

It’s a question particularly poignant this week, as librarians and booksellers celebrate Banned Books Week. A “virtual read-out” pushes the boundaries on YouTube of what is considered appropriate reading.

I got my answer from a reader recently. She wrote that the experience of immodesty, that brazen state of a woman’s rebellion against the prescribed life, was lost to her. But last year, “for the briefest few hours,” she got it back. When she did, she wrote, “I dazzled and was electrified. And then I was shamed, and shattered, and shuffled out of the room.”

There is something good about trying out what we’re told is wrong. Something brave. At the time of my book, the generation following the Revolution, people were figuring out what freedom meant. And one thing it meant was reading what your betters commanded that you avoid. Henry Garland, a rebel son of Puritans, sells the top two bestsellers from his carriage: The Bible, and Noah Webster’s The Book of Spelling, a dry-sounding title that was a how-to manual for teaching yourself to read. The next hot-selling book seems to have been a tie.

• The Coquette, sometimes called the first American novel, told the story of a woman torn between an upright but boring preacher and a handsome Southern rake. She ends up pregnant, shunned, but sympathetically so – and the book swiftly is banned from the new public libraries.

• Aristotle’s Masterpiece, despite the lofty title, concealed a ‘granny book’ or midwife’s manual –with illustrations, and explicit instructions on how to make a woman ready to conceive.

And then there was Fanny Hill. Now a classic of erotic literature, it follows an orphaned girl into the English urban sex trade – where she has a lot of fun. It could be called that generation’s The Joy of Sex.

Not all of these books were formally banned because the government hadn’t yet taken on that role – but they were certainly forbidden. From the pulpits, in the self-censorship of the newspapers which advertised Fanny Hill obliquely as “Memoirs of –”, people got the message: Don’t go there.

So they went. What is it about the forbidden that actually can drive us to be better people, even better citizens? Sometimes the content itself is liberating. But even more, it’s the experience of navigating that border territory where right and wrong are unclear. There, you find out what you yourself feel is right. Our forebears overthrew monarchies. They did not live as they were told to do. They invented a better way. And sometimes the first step is to do what is banned. Forbidden.

Freedom requires moral courage. And moral courage often arises out of the ashes of moral failure – out of shuffling shamefacedly out of the room, as happens to my characters. You have to be lost to be found.

This article also appears at Elle Lit and The King’s English Bookshop Blog.