While the words of King Hamlet to his son are to revenge his death, the play Hamlet is not simply a revenge play, for the revenge of the ghost to which Hamlet has sworn is enacted only in the final act. Rather, Hamlet is a "dialectical revenge play" as one critic terms it. For, the resolution of the revenge plot is mired in veils of illusion and conflict that demonstrate the incommensurability of revenge.
While the death of King Hamlet disrupts the realm of the Danish court, it is not the king's death which effects the action; instead it is the dialectic that Hamlet has with death and life that moves the tragedy because justice calls for his life. Shakespeare's longest play is an existential one: "To be, or not to be" is, indeed, the question at the crux of the drama.
That the play is dialectical is evident in the seven soliloquies of Hamlet that direct the movement of the play; for, most of these soliloquies are reflective of Hamlet's great self-debate about avenging his father's murder.
In his first soliloquy, for example, Hamlet expresses his anger against his mother for so quickly marrying after the death of her husband. And, in his second soliloquy, after seeing King Hamlet's ghost, he rails further against his mother, calling her a "damned villain" while he promises to avenge his father's death, "I have sworn't." Yet, Hamlet does not proceed with this revenge until the final act. While he delays this action, he recriminates himself for not doing something when a player in fictional The Murder of Gonzago displays so much more emotion than he,
Had he the motive and the cue for passion
That I have? He would drown the stage with tears,
And cleave the general ear with horrid speech,
Make mad the guilty....
Why, what an ass am I!...
Must...unpack my heart with words....(2.2.537-540)
But, in his next soliloquy, Hamlet is still passive, reflecting on existence and how it would be better to "sleep, to say we end," but "conscience doth make cowards of us all"(23.1.83). Finally, after he observes Fortinbras, a "delicate and tender prince," who fights for a parcel of land that has been taken from his father, Hamlet is shamed into action, declaring, "This is I,/ Hamlet the Dane" (5.1.227-228)
With Ophelia, Hamlet is, perhaps, more verbally vengeful than with any other character because he knows that their conversation is being overheard and he feels betrayed. He acts as though he no longer loves her, "I did love you once"; he insults her with lewd words as they wait on the play's beginning. But, he continues his dialogue with revenge as inadequate after she dies and he declares his love for her to Gertrude in the graveyard scene.
Likewise, his veiled illusions with his former friends result in their revenge deaths as do Hamlet's angry words with Polonius, as well as his words with Gertrude that result finally with her death--her sacrifice, perhaps, for her son as she drinks from the cup intended for Hamlet. Certainly, this death, too, is incommensurable for Hamlet as is that of Laertes, who tells Hamlet, "The foul practice/Hath turned itself on me" (5.2.296-297).
The final act of revenge is the only one that is satisfying to Hamlet-
Here, thou incestuous, murd'rous, damned Dane,
Drink off this potion. Is thy union here?
Follow my mother. (5.2.303-305)
As he dies Hamlet concludes his dialectic, giving Fortinbras his "dying voice."