is the mightier," and, indeed, Hamlet seems to have gotten even crazier than he was in the previous three Acts. Hamlet continues to behave like a person who has come unhinged, messing with the minds ofRosencrantz and Guildenstern, hiding Polonius' body, and antagonizing Claudius and the court.

Act Four, Scene Four also contains an important soliloquy in which Hamlet considers his lack of action over the murder of his father in comparison to the war being waged over something as meaningless as a small plot of land. He tells himself to have his "thoughts be bloody, or be nothing worth," which marks a renewed commitment to his plans for revenge. Overall, Act Four seems to suggest that Hamlet is now erratic enough to commit the murder he's so fervently been contemplating over the course of the play.

Hamlet becomes increasingly erratic in his behavior. This causes quite a bit of questioning on Hamlet's sanity. His lack of avenging his father's death has turned into despair. His reluctance to act is lessening by the end of act IV, and in act v he will be ready, at last.

Hamlet appears to become more aggressive and determined during the course of Act 4 in Shakespeare's Hamlet.  Of course, this isn't the first time he has shown aggression or determination, so whether the act demonstrates actual change might be a matter of opinion.

Hamlet feels rebuked again in Act 4, this time by Fortinbras's army (Act 4.4).  He concludes his thoughts with:

...Oh, from this time forth,

My thoughts be bloody, or be nothing worth!  (4.4.64-65)

The army Hamlet sees is on its way to fight and die for a worthless piece of land.  If these soldiers are willing to do this for almost nothing, Hamlet reasons, how terrible is it that he has a father to revenge, and yet has so far done nothing.  His resolution strengthens and he is determined to carry out his revenge. 

In Shakespeare's Tragedy of Hamlet, Hamlet had been quite indecisive in Acts I and II.  In Act III, he kills for the first time (Polonius).  This is important, even though it is by mistake.  As a result, in Act IV, Hamlet is more focused on his role as avenger: he has killed and can kill again.  Indecision is a memory.

In Acts I-III, Hamlet was unsure of who was who: Was his father's ghost telling the truth?  Did Claudius really kill his father?  Was his mother in on the murder?  Could he really kill his uncle?  Now, in Act IV, Hamlet knows that Claudius is a villain; therefore, Hamlet can anticipate his moves better.

In Act IV, Hamlet willingly goes to England, even though he is meant to be killed there.  Knowing this, Hamlet plays both a verbal and physical game of cat and mouse.  Upon his return,  he will have the upper hand: he will be the cat.  As a result, his use of verbal irony (sarcasm) increases giddily:

My mother: father and mother is man and wife; man and wife is one flesh; and so, my mother.  Come, for England!

Hamlet is so giddy, he even plays hide-and-seek with Polonius' body.  He says to Claudius:

Hide fox, and all after.  (an old signal cry for the game of hide-and-seek)