"Who controls the past controls the future: who controls the present controls the past," repeated Winston obediently.
"Who controls the present controls the past," said O'Brien, nodding his head with slow approval. "Is it your opinion, Winston, that the past has real existence?" (3.2.39-40)
O'Brien smiled faintly. "You are no metaphysician, Winston," he said. "Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?"
"Then where does the past exist, if at all?"
"In records. It is written down."
"In records. And- ?"
"In the mind. In human memories."
"In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?"
"But how can you stop people remembering things?" cried Winston again momentarily forgetting the dial. "It is involuntary. It is outside oneself. How can you control memory?
You have not controlled mine!" (3.2.42-49)
"You believe that reality is something objective, external, existing in its own right. You also believe that the nature of reality is self-evident. When you delude yourself into thinking that you see something, you assume that everyone else sees the same thing as you. But I tell you, Winston, that reality is not external. Reality exists in the human mind, and nowhere else. Not in the individual mind, which can make mistakes, and in any case soon perishes: only in the mind of the Party, which is collective and immortal. Whatever the Party holds to be the truth, is truth. It is impossible to see reality except by looking through the eyes of the Party. That is the fact that you have got to relearn, Winston. It needs an act of self- destruction, an effort of the will. You must humble yourself before you can become sane." (3.2.51, O’Brien)