Unpublished letters and postcards that shed light on the final, tortured years of Franz Kafka have gone on sale at a Viennese antiquarian book shop for £800,000.
The letters, which were written between 1921 and 1924, when the writer died of tuberculosis, were addressed to his closest friend, Robert Klopstock, an Hungarian doctor and writer.
A total of 38 letters and cards written in a scrawled German hand are for sale. Seven have never been published and a further 14 have had only extracts published.
"The mere fact that these letters are original Kafka letters makes the find extraordinary," Dr Alfred Schmidt, of the Austrian National Library, said. "Kafka is a writer whose life and everything he wrote has been so thoroughly researched that every line that he wrote is significant."
Scribbled across many of the letters are notes by Kafka's lover, Dora Diamant, whom he met and fell in love with in 1923. Just before Kafka's death in June 1924 in a sanatorium at Kierling, near Vienna, she wrote: "The doctors here have no more options. They have absolutely given up. Desperation made me think that maybe homoeopathy or something similar might help. There is nothing to lose.
"The clinic where Franz is is terrible. It is going to speed up his end. He is in a room with two people who are in a terrible state. The beds are packed alongside each other. He can't eat, can't speak, Robert, help, give me advice what to do?"
Hugo Wetscherek, of the Inlibris bookshop, which is playing host to the sale of the collection, said: "We have a mixture of letters and postcards. Experts believe that he used the postcards because they were cheaper than letters and he did not have much money. The letters and postcards are written in black and blue ink as well as pencil. The postcards are written on each side and therefore the length in average equals those of his letters."
The last Kafka sale featured a single, already published letter that fetched £30,000 in Berlin in 2001.
Kafka was born in 1883 in Prague, the eldest child of a wealthy Jewish shopkeeper. From an early age he felt isolated from his family, rarely seeing his mother and fearful of failing to please his father. He had complicated relationships with various women, including Felice Bauer, to whom he was engaged twice but never married.
In 1923 he met the Polish-born Dora Diamant and the couple moved to Berlin. She stayed near by during Kafka's various stays in hospital and was with the writer when he died. Just before his death, Kafka asked Diamant's father for permission to marry her, but was refused.
Kafka became famous for his essays and short stories such as Die Verwandlung (1916, The Metamorphosis), Der Prozess (1925, The Trial) and Das Schloss (1926, The Castle).