This is an important soliloquy in the play for a number of reasons, but principally because it gives us and Hamlet final proof that Claudius is indeed guilty of what the Ghost accuses him of: a sin so old that it "hath the primal eldest curse upon't." The murder of a brother would have been recognised as yet another instance of Cain's murder of his brother, Abel, in the Book of Genesis in The Bible. Claudius in this soliloquy is therefore shown to struggle with his tremendous guilt and fear of punishment, but at the same time he is equally shown to struggle between his desire to be forgiven for this terrible crime and his reluctance to give up what he gained through committing it: the crown and Gertrude:
Forgive me my foul murder:
That cannot be, since I am still possess'd
Of those effects for which I did the murder,
My crown, mine own ambition, and My Queen.
May one be pardon'd and retain th'offence?
This soliloquy therefore presents us with a man who is sharply divided by his guilt on the one hand, and yet his unwillingness to give up what he killed to gain on the other. Such an internal conflict would have been interesting to an Elizabethan audience who were a Christian people.