Outside, even through the shut window-pane, the world looked cold. Down in the street little eddies of wind were whirling dust and torn paper into spirals, and though the sun was shining and sky a harsh blue, there seemed to be no colour in anything, except the posters that were plastered everywhere. The black-mustachio'd face gazed down from every commanding corner. There was one on the house-front immediately opposite. BIG BROTHER IS WATCHING YOU, the caption said, while the dark eyes looked deep into Winston's own […] In the far distance a helicopter skimmed down between the roofs, hovered for an instant like a bluebottle, and darted away again with a curving flight. It was the police patrol, snooping into people's windows. The patrols did not matter, however. Only the Thought Police mattered.

Basic set up:

Winston Smith, the protagonist of Orwell's novel, walks through the streets, followed by the eyes of Big Brother. Dum dum dum.

George Orwell's 1984 is an allegory about totalitarianism. Totalitarianism is absolute dictatorship. Democracy? You can forget about that in a totalitarian society. Freedom? Ha. Hahahaha.

1984 was published just a few years after World War II ended in 1945. And a lot of the terrible carnage of World War II happened, of course, because of totalitarian leaders like Hitler in Germany.

In the above passage, Orwell is beginning to show us the ugly side of totalitarianism. The novel is set in a society where you're being watched at every turn, just as Winston is (Big Brother is always watching him). Agents of the totalitarian party snoop at people through their windows. There's no freedom in this world.

When Orwell's book was written it was set decades in the future. But Orwell was talking about the rise of totalitarianism in his own time and he was showing his readers where it could lead. So even though the book is set in the "future" (for us it's the past now, of course), it's really an allegory about Orwell's own time.

A lot of the power of this passage comes from the imagery. We've probably heard of "Big Brother" before, even if we haven't actually read 1984. Big Brother first pops up in Orwell's novel as an image and a symbol of totalitarian oppression.

The image of Big Brother is all over this novel. Posters of Big Brother hang everywhere, reminding the characters—and us readers—that we can't escape his creepy gaze: "The black-mustachio'd face gazed down from every commanding corner. There was one on the house-front immediately opposite. BIG BROTHER IS WATCHING YOU, the caption said, while the dark eyes looked deep into Winston's own."

All of the control and repression that is part and parcel of totalitarian regimes is captured in this image of Big Brother. Through the imagery, Orwell manages to suggest to us just how oppressive and creepy totalitarianism really is.