The proof-reader's dilemma: The History of the Siege of Lisbon

Moving along with the weirdly postmodern and very European The History of the Siege of Lisbon, the errant proof-reader, who willfully inserted the word "not" in a key passage of the eponymous history, which he is editing, gets called on the carpet by the publishing house for whom he works on a piecemeal basis. He, obviously, can't explain why he intentionally made a mistake - completely upending the very purpose of proof-reading. Oddly, the author of the book isn't especially upset, and the publisher places an "erratum" note in all copies of the book. Publisher decides create a new position, an editor to oversee all proofreading, and the proof-reader, Raimundo Silva, believes she will be his antagonist (although he's also attracted to her - he's a guy with seemingly no relations with any friends, relatives, or lovers). She calls him back to the office - he's sure he will be fired - but she makes him a strange offer: she presents him with the only copy of the book without the erratum note and suggests he completely rewrite the book as his own, a history of the siege in which the crusaders did not stop in Lisbon to help oust the Muslim population and install a Christian government. He goes home in a terrible rainstorm to ponder this offer. So, again, as throughout the novel, author Jose Saramago plays with the thin membrane that separates truth from fiction, noting how easy it is for historians, let alone novelists, to play with an alter the facts and thereby alter our perceptions of the past - and in fact, of everything. As readers, we have to question: whose novel are we reading? Saramago's? Silva's? The unnamed original author's? Our own?