What is the book Winston reads about in "1984"? What does he realize after?Goldstein's “The Theory and Practice of Oligarchical Collectivism”...

Throughout George Orwell’s 1984, the semi-mythical figure of Emmanuel Goldstein runs like a thread throughout Orwell’s narrative.  A one-time highly-revered figure in the Party, he is now considered society’s most despised counter-revolutionary.  He is, as Orwell notes early in his novel, “the Enemy of the People,” a traitor who has dedicated himself to undermining the very Party he was instrumental in creating.  The father of the Party’s founding creeds, Goldstein was now reviled for his transformation into a liberal advocating on behalf of such subversive ideals as “freedom of speech, freedom of the Press, freedom of assembly, freedom of thought.”

Winston, of course, has long been disenchanted with the Party’s totalitarian system, with its repressive measures and the dehumanizing nature of its rule.  He has subtly and discreetly maneuvered himself away from the thought-control that the Party imposes on its subjects, and he has grown weary of the omniscient presence of Big Brother.  To Winston, the figure of Emmanuel Goldstein represents liberation from everything that he has grown to hate.  It is, therefore, ironic that his eventual exposure to Goldstein’s book, initially and derisively referred to simply as “The Book,” but more formally titled The Theory and Practice of Oligarchical Collectivism should awaken in him a subservience to the Party that is truly transformative.  It is in Chapter Nine of Orwell’s novel that Winston sits down with Goldstein’s tome and is exposed, for the first time, to the doctrinal genesis of the system he had grown to loathe.  Goldstein’s book, of course, is divided into chapters each of which, Winston discovers, provided the intellectual underpinnings of the Party’s approach to governing.  Chapter I, for instance, is titled “Ignorance is Strength,” Chapter III is titled “War is Peace,” and so on.  Orwell devotes a considerable portion of his novel to Goldstein’s manifesto, and its effects on Winston are profound.  His first reaction upon reading it is to try to get Julia interested in it.  That 1984 will end with Winston firmly entrenched in the system he once disavowed was illustrative, from Orwell’s perspective, of the power of words on the human mind, and the most powerful words, too often, came out of the mouths of those least inclined toward concepts like freedom.