Hamlet has spent much of Acts 1-3 procrastinating, some might even say vacillating, in avenging his father's death. He is an intelligent, sensitive, introspective young man by nature, and he spends much of his time deep in thought, pondering the evil that seems to surround him and the nature of life (and death) itself. By the end of Act IV, with the knowledge (thanks to the play) that Claudius is indeed guilty of the murder, Hamlet turns a corner of sorts. After a bitter soliloquy in which he chastises himself for what he deems cowardice, he determines to "let my thoughts be bloody, or be nothing worth!" In Act V, Hamlet returns to England with more purpose. After his struggle with Laertes at Ophelia's funeral, he determines to push ahead with his plan, come what may. After telling Horatio about the king's plot to have him beheaded, Hamlet essentially tells him that he views himself as justified in killing him:
Does it not, think thee, stand me now upon—
He that hath kill'd my king, and whored my mother;
Popp'd in between the election and my hopes;(70)
Thrown out his angle for my proper life,
And with such cozenage—is't not perfect conscience
To quit him with this arm? And is't not to be damn'd
To let this canker of our nature come
In further evil?
Hamlet further intimates that he will kill Claudius before he discovers what happened to Guildenstern and Rosencranz in England:
It (the time before Claudius finds out) will be short; the interim is mine/And a man's life's is no more than to say 'One.'