What is the theme in Rosencrantz and Guildenstern Are Dead by Tom Stoppard?

The human condition is at the heart of Stoppard's play. Stoppard's Rosencrantz and Guildenstern Are Dead blends two stories Shakespeare's Hamlet and Stoppard's own version of how the two courtiers might have felt and behaved after they were summoned by King Claudius to spy on their schoolmate, Hamlet.