The tele-screen received and transmitted simultaneously. ... There was of course no way of knowing when you were being watched. How often, or on what system, the Thought Police plugged in on any individual was guesswork. At any rate they could plug in to your wire whenever they wanted to. You had to live — did live, from habit that became instinct — on the assumption that every sound you made was heard, and ... every movement scrutinized." — George Orwell, "1984"