In the room with the dials, O'Brien makes Winston look in the mirror at his filthy body. I understand that this is used as a mechanism of torture to make him see that they have power over him. But what I don't understand is why O'Brien said he was the last man. Don't they continue to capture thought criminals? They watched Winston for seven years, waiting for the right time to catch him. So they must be after other people too, right?

