For the first time, a new digital technology has enabled people to see the previously unseen passages from Charles Dickens' manuscripts.
The technique, which removes his crossings-out and corrections, allows researchers to discover how the author shaped and reshaped his prose.
The Victoria and Albert Museum pilot study focused on his Christmas story, 'The Chimes', using technology that was developed by Ian Christie-Miller, a former visiting research fellow at London University.
"We're talking of tens of thousands of manuscript pages that could potentially be unlocked," the Independent quoted Florian Schweizer, director of the Charles Dickens Museum in London, as saying.
The technique, separating layers of text, involves combining two or more digital images - a frontlit and backlit image of a page.
By digitally subtracting one from the other, differences are easily revealed.
In 'The Chimes', the tests showed for example that the published sentence - "Years ... are like Christians in that respect" - originally read: "Years ... are like men in one respect."
"Why did he make that change? Quite a change. Literary scholars will ask themselves those questions," Dr Schweizer said.
Rowan Watson, a senior curator at the V and A, described Dr Christie-Miller's technology as "ingenious and inspiring".
The manuscripts show Dickens "almost thinking aloud on to paper," he added.