What happened in the unseen labyrinth to which the pneumatic tubes led, he did not know in detail, but he did know in general terms. As soon as all the corrections which happened to be necessary in any particular number of the Times had been assembled and collated, that number would be reprinted, the original copy destroyed, and the corrected copy placed on the files in its stead. This process of continuous alteration was applied not only to newspapers, but to books, periodicals, pamphlets, posters, leaflets, films, sound-tracks, cartoons, photographs – to every kind of literature or documentation which might conceivably hold any political or ideological significance. Day by day and almost minute by minute the past was brought up to date. In this way every prediction made by the Party could be shown by documentary evidence to have been correct; nor was any item of news, or any expression of opinion, which conflicted with the needs of the moment, ever allowed to remain on record. All history was a palimpsest, scraped clean and re-inscribed exactly as often as was necessary. In no case would it have been possible, once the deed was done, to prove that any falsification had taken place. The largest section of the Records Department, far larger than the one in which Winston worked, consisted simply of persons whose duty it was to track down and collect all copies of books, newspapers and other documents which had been superseded and were due for destruction. A number of the Times which might, because of changes in political alignment, or mistaken prophecies uttered by Big Brother, have been rewritten a dozen times still stood on the files bearing its original date, and no other copy existed to contradict it. Books, also, were recalled and re-written again and again, and were invariably re-issued without any admission that any alteration had been made. Even the written instructions which Winston received, and which he invariably got rid of as soon as he had dealt with them, never stated or implied that an act of forgery was to be committed: always the reference was to slips, errors, misprints or misquotations which it was necessary to put right in the interests of accuracy.