A set of Samuel Beckett jotters, regarded by literary experts as one of the 20th century's finest manuscripts, is expected to sell for about £1 million at auction.
Six exercise books of the writer's work on his first novel Murphy, and only seen by a handful of people, are being offered by Sotheby's in London next month.
The auctioneers said the notebooks will give a unique insight into how the Nobel laureate's mind worked.
Handwritten in Dublin and London between August 1935 and June 1936 while Beckett was undergoing psycho-analysis, the books are full of revisions, doodles and sketches of his contemporaries James Joyce and Charlie Chaplin.
Peter Selley, of Sotheby's, said: "This is unquestionably the most important manuscript of a complete novel by a modern British or Irish writer to appear at auction for many decades. I have known about the existence of this remarkable manuscript for a long time - as have a number of others in the rare book business and some Beckett scholars - but it has only been glimpsed, tantalisingly, by a few chosen individuals during that time.
"The notebooks contain almost infinite riches for all those - whether scholars or collectors - interested in this most profound of modern writers, who more than anyone else, perhaps, captures the essence of modern man."
The 800-page manuscript has been in private hands for decades. Sotheby's put a guide price of £800,000-£1.2 million on it. Entitled Sasha Murphy, the notebooks contain hundreds of cancellations and revisions, and the text is substantially different from the published version, Murphy.
It includes at least eight cancelled versions of the famous opening sentence before Beckett settled on: "The sun shone, having no alternative, on the nothing new." Beckett said late in life that the book should be seen as a guide to understanding his work. Each entry is dated, giving an insight into Beckett's working processes, including periods of writer's block.
The Irish writer, who lived in Paris for most of his life, was awarded the Nobel Prize for Literature in 1969.
The Beckett work is the centrepiece in Sotheby's sale of English Literature, History, Children's Books and Illustrations, in London on July 10. Auctioneers expect it to beat the £900,000 paid for a partial draft of Joyce's Ulysses sold at the turn of the century.