In this scene we see two new characters, Rosencrantz and Guildenstern, childhood friends of Hamlets. They have been sent by the king,Claudius, to help discover why Hamlet's behaviour has changed, and to find out whether he is actually mad.

"The need we have to use you did provoke...something you have herd of Hamlets transformation"

The two men pretend to be visiting Hamlet.

This is an important part of the play, as it shows that Hamlet is getting to Claudius, worrying him, he feels threatened by Hamlet and his behaviour.

Next Polonius enters, he brings news that the ambassadors from Norway have returned and that he has found the cause of Hamlets lunacy. Naturally Claudius is more interested in the second point. Polonius exits before telling the king, Gertrude says the cause is clearly obvious,

"His father's death and our o'erhasty marriage."

This shows that Gertrude is...