The precise metaphysical procedures by which a book goes about writing another book need not concern us here. Suffice it to say that our human scribes remain entirely ignorant of their possession by bibliographic forces; the agent in question never doubts that his authorship is authentic. A bit of literary history may clarify matters. Unlike Charles Dickens's other novels, Little Dorrit was in fact written by the Faerie Queene. It is fortunate that Jane Austen's reputation does not rest on Northanger Abbey, for the author of that admirable satire was Paradise Regained in a frivolous mood. The twentieth century offers abundant examples, from the Pilgrim's Progress cranking out Atlas Shrugged, to Les Miserables composing the Jungle, to the Memoirs of Casanova penning Portnoy's Complaint.
Occasionally, of course, the alchemy proves so potent that the appropriated author never produces a single original word. Some compelling facts have accrued to this phenomenon. Every desert romance novel bearing the name E.M.Hull was actually written by Madame Bovary on a lark; Mein Kampf can claim credit for most of the Hallmark greeting cards printed between 1958 and 1967; Richard Nixon's entire oeuvre traces to a collective effort by the science-fiction slush pile at Ace Books. Now, as you might imagine, upon finding a large readership through one particular work, the average book aspires to repeat its success. Once the Wasteland and Other Poems generated its first Republican Party platform, it couldn't resist creating all the others. After Waiting for Godot acquired a taste for writing Windows software documentation, there was no stopping it.

--The Last Witchfinder, James Morrow (2006)