Show how spying is important in the play Hamlet.

Spying is a recurring event in the play that brings about
the death of Polonius as well as the deaths of Rosencrantz and Guildenstern. In Act 2,
sc. 1, Polonius even has his son spied upon when he tells Reynaldo spy on his son,
Laertes.  Later, in Act 3, sc. 1, both Polonius and Claudius spy on Hamlet during his
"To be or not to be..." speech.   Act 3, sc. 4, Polonius again decides to spy on Hamlet
in Gertrude's room.  He wants to find out why Hamlet has been acting they he's been
acting and he hides behind the arras.  Hamlet, in his anger with his mother over
Claudius' actions and her possible involvement, realizes someone is behind the tapestry
and stabs it, killing Polonius.  When Hamlet is sent to England, he manages to get the
letter that Claudius has sent with Rosencrantz and Guildenstern and by employing his spy
techniques (opening the letter, rewriting it, resealing it), he changes the order in it
to save himself and have Rosencrantz and Guildenstern put to
death.