Twentieth Century Fox
The book: The Modern Library ranked "The Sound and the Fury" sixth on its list of the 100 best English-language novels of the 20th century. It was part of the body of work that got William Faulkner the Nobel Prize in Literature in 1949.
Why it's unfilmable: The stream-of-consciousness narrative, the jumping around in time, the density of language ... take your pick.
The movie: "The content -- or lack of content -- in the film that Jerry Wald has produced from William Faulkner's 'The Sound and the Fury' inevitably calls for a quote, said quote being the lines in Shakespeare's 'Macbeth' from which that title is evidently derived. 'It is,' says Macbeth, soliloquizing on the emptiness of life, 'a tale told by an idiot, full of sound and fury, signifying nothing.' And that, we'd say, is a reasonably accurate description of Mr. Wald's talkative film." -- Bosley Crowther, New York Times