The alteration of the past is necessary for two reasons…

““The alteration of the past is necessary for two reasons, one of which is subsidiary and, so to speak, precautionary. The subsidiary reason is that the Party member, like the proletarian, tolerates present-day conditions partly because he has no standards of comparison. He must be cut off from the past, just as he must be cut off from foreign countries, because it is necessary for him to believe that he is better off than his ancestors and that the average level of material comfort is constantly rising. But by far the more important reason for the readjustment of the past is the need to safeguard the infallibility of the Party. It is not merely that speeches, statistics, and records of every kind must be constantly brought up to date in order to show that the predictions of the Party were in all cases right. It is also that no change in doctrine or in political alignment can ever be admitted. For to change one’s mind, or even one’s policy, is a confession of weakness. If, for example, Eurasia or Eastasia (whichever it may be) is the enemy today, then that country must always have been the enemy. And if the facts say otherwise, then the facts must be altered. Thus history is continuously rewritten. This day-to-day falsification of the past, carried out by the Ministry of Truth, is””

— George Orwell