In the rest of the play, Hamlet, in every way possible, puts obstacles in his own path. He develops fits of melancholy, contemplates suicide, seeks proofs where he needs none, tempts his uncle to take action against him, drives his fiancée to suicide, kills an innocent, if garrulous, father-figure, allows himself to be shipped abroad, arranges to murder two erstwhile friends, and finally does what he must do in an inordinately complicated way involving a great deal of happenstance. Like Oedipus, Hamlet seeks to avoid doing what he swore to do, but both proved powerless to halt the march of fate they evoked in their vows.

When discussing Hamlet, and especially the forces that shape his actions, we should understand the significance of the revenge motif in human life as well as a dramatic theme in Elizabethan England. The very essence of revenge is its disproportionateness, its excess beyond the offense. Revenge is characterized by escalation. Talion justice demands no more than an eye for an eye; revenge demands two eyes or more. For Hamlet to refrain from killing Claudius, as he easily might have done as he watched Claudius pray, speaks not only to Hamlet's indecisiveness, but also to his awareness that the obligation his father placed on him was for revenge, not merely justice. In Hamlet's words, a quick dispatch of Claudius at the earliest moment would be no more than "hire or salary," not revenge.

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While Hamlet hesitates about avenging his father and contemplates the alternative paths his revenge might take, the work of sworn vengeance  proceeds inexorably. Although Hamlet delays acting on his father's charge to take vengeance against Claudius while sparing his mother ("leave her to heaven"), he manages to become the agent of destruction of another woman, Ophelia, onto whom his hatred for womankind has become displaced, and of another father, Polonius, who stands in his way to her. Whatever other purposes the deaths of Polonius and Ophelia might serve in the play, they also demonstrate the characteristic helplessness of man in the grip of a vow-become-compulsion. Delay as Hamlet may, his vow fulfills itself as much through his efforts at avoidance as by his more direct actions and sweeps the innocent and the guilty, agonists and bystanders before it.

In support of the theory that Hamlet could not acquit his obligation to avenge his father's murder simply by bringing Claudius to justice, notice that at the very end of the play Hamlet finally achieves justice. After Laertes stabs him with a poisoned sword, and Hamlet dispatches him in turn, Hamlet turns the sword on the King as well. Now Claudius's death is assured and justice is served, but Hamlet's revenge is not, inasmuch as he could have slain Claudius in the same way while Claudius was kneeling at prayer. As Hamlet himself is dying, he becomes the avenger in the true spirit of that role by forcing the poisoned wine between the lips of the already-dying Claudius. Thus Claudius dies twice: once in an unpremeditated and ironic way with the poisoned foil he had prepared for Hamlet, and again in acquittal of the premeditated vengeance that Hamlet held in mind for him throughout the play. Hamlet's reluctance to be the avenger persists to the end; constrained by unconscious guilt, he does not act the avenger until he too is about to die, and until the murder he has planned and delayed has become redundant.

Once Hamlet, like Oedipus, has reached the point of no return, there is no way out but to allow his promise to animate him, come what may, until its ultimate resolution. We cannot imagine Hamlet, or the hero of a Greek tragedy or of a grand opera for that matter, prudently changing his mind once he had sworn upon a course. The driving force and meaning of the work of art would be lost. The dramatic power of the work rests on the audience's expectation that, come what may, the hero will become the instrument of his vow and will fulfill his promise, in spite of all obstacles and in spite of his own reservations.

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Ella Freeman Sharpe (1948) commented on Hamlet's procrastinating that "the organic functional basis of the whole play is revealed, for example, in the fact of Hamlet's procrastination. If we disregard for the moment the more familiar Oedipal explanation in relation to the killing of Claudius and consider only the effect of procrastination and its final result, we get both a simple pattern of bodily functioning as such and a basis for Aristotle's recognition of the cathartic function of great tragedy."

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Sharpe reminds us about the infantile source of procrastination that: "An infant's emotional and bodily discharge is immediate and spontaneous and procrastination plays no part in it. The ability to procrastinate, which is so distinctive of the play as a whole is a memorial to a later emotional situation which resulted, not in return to heaven, but in dethronement and banishment.

A young child who has acquired sphincter control may revert to incontinence under emotional stress. . . In other words, a child may procrastinate by withholding his bowel contents until evacuation can no longer be prevented and a 'catastrophe' occurs."

In that passage, Sharpe refers to some fundamental facts about human development that are important in understanding promising. She reminds us that procrastination, that is, the capacity to delay, is not part of the psychology of early infancy. . . It also is the beginning of mastery over impulse, of the development of thinking independent of acting, and of the development of the sense of autonomy from parents and from instinct. The ability to say "no" in the first instance when the infant turns his face away from the breast carries with it the beginning of a sense of having will. In holding that the development of autonomy is first manifested in the ability to delay, with roots in anal psychosexuality, Sharpe bids us notice that the autonomy achieved is, by this very source, limited. It is a relative delay, a relative autonomy. What the bowel has promised it must sometime deliver. Likewise, the separation of thought and action so based is limited. That which must come must come. That which shall be shall be.

 - Herbert J. Schlesinger, Promises, Oaths, and Vows: On the Psychology of Promising