You are prepared to cheat, to forge, to blackmail, to corrupt the minds of children, to distribute habit-forming drugs, to encourage prostitution, to disseminate venereal diseases—to do anything which is likely to cause demoralization and weaken the power of the Party? If, for example, it would somehow serve our interests to throw sulphuric acid in a child’s face—are you prepared to do that?

O’Brien is interviewing Winston and Julia when they have come to his apartment and reveal themselves as enemies of the Party. They believe that he is testing the limits of their commitment to overthrowing the party, but Winston later learns that O’Brien is recording their response to use it as an example of how depraved they are.

They got me a long time ago.

When Winston first sees O’Brien at the Ministry of Love, Winston assumes that the Thought Police have arrested O’Brien. O’Brien’s response that they got him long ago may be interpreted as meaning simply that he has served the Thought Police for a long time, or that he was once himself against the Party, but turned to its service.

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.

In this quote, O’Brien lays out one of the core concepts of the Party between sessions of torturing Winston. Winston had always understood that the Party sought to control truth, but O’Brien makes it clear that the Party sees itself as the only lens through which truth can even be defined. This perspective allows the Party to say that 2+2 = 5.

The first thing for you to understand is that in this place there are no martyrdoms.

Here, O’Brien makes sure Winston understands that he will not die resisting the Thought Police and become a symbol for other rebels. The Thought Police have learned that they must convert their enemies to the Party’s way of thinking before killing them to ensure that others are not inspired by stories of thought-criminals who never give up their beliefs.

Never again will you be capable of love, or friendship, or joy of living, or laughter, or curiosity, or courage, or integrity. You will be hollow. We shall squeeze you empty, and then we shall fill you with ourselves.

O’Brien describes the goal of the Thought Police in converting thought-criminals. Any aspect of human nature which allows resistance to the Party is systematically eliminated through torture. All that’s left is the Party and love for the Party. This condition accurately describes Winston as the reader sees him in the final chapter of the book.

If you want a picture of the future, imagine a boot stamping on a human face—forever.

In this quote O’Brien is not merely being aggressive or insulting to Winston’s hope for a successful overthrow of the Party. O’Brien is also explaining that the Party must have resistance in order to exist. There will always be traitors. Even if people stop rebelling against the party, the Party will manufacture new traitors so that it can be seen crushing them. This act of crushing opposition is part of how the Party defines itself and maintains its power.