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...the single assumption that makes our existence viable - that somebody is watching....
— Tom Stoppard • Rosencrantz & Guildenstern Are Dead

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The fragment makes the belief that somebody is watching a condition of viable existence. One reading is that an audience gives actions their significance. Its sweeping claim places observation at the centre, while leaving open who watches and why their attention should matter so much.
Context reviewed