According to The Telegraph, the scrap of paper features a fragment copied out by the author from a sermon written by her brother, the Rev James Austen.
Now conservation experts are painstakingly lifting the snippet from the book it is stuck into so scholars can read the mysterious words she wrote on the back.
The passage in Austen’s handwriting, dating from 1814, states: "Men may get into a habit of repeating the words of our Prayers by rote, perhaps without thoroughly understanding – certainly without thoroughly feeling their full force & meaning.”
This reflects a theme that she wrote about in her novel 'Mansfield Park,' which was published in the same year.
The small piece of manuscript is glued into a first edition dating from 1870 of 'The Memoirs of Jane Austen,' by the novelist’s nephew, James Edward Austen Leigh.
David Dorning, a conservator at West Dean College in Chichester, West Sussex, has the job of removing it from the book so the passage on the back can also be seen.
“When I initially read it, I thought it was the sort of thing that Jane Austen might write. Then I realised that it was a sermon by her brother. I thought maybe all the Austens felt like that about men,” he joked.
Mr Dorning added: “You can see clearly that the fragment has writing on the back. But because it’s been pasted down nobody knows what it says - presumably it’s more of the same sermon.
“It is fixed into the book so we have got some unsticking to do. It is almost certainly stuck together with some kind of water-soluble adhesive. We need to get it damp.
“I will be humidifying it gently to enable the adhesive to soften so that at some point it will be possible to lift it.”
The book containing the scrap of text was recently bought by Jane Austen’s House Museum at Chawton in Hampshire with the aid of funding from the Jane Austen Society.
It will feature in an exhibition at the museum later this year to mark the bicentenary of Mansfield Park.