"Vengeance is mine; I will repay, sayeth the lord" (Romans.xii.19). This Bible verse is quoted by Hieronimo in Act III, scene xiii, and it can be said to epitomize the official Elizabethan attitude toward revenge: that it is something that should be left to God. But this position is silent on the relationship between revenge and justice, which are are identified with each other throughout the play—Hieronimo makes the connection explicitly several times, and revenge is officially sanctioned by Proserpine (Persephone), the Queen of the Underworld, in the play's opening scene. Revenge should be performed by God (or the State, which derived its power from God), but it still needs to be performed. This is the presupposition that underlies Hieronimo's doubts whether the Heavens (and God) are in fact just, which are doubts he expresses after the murder of his son and the apparent escape of his murderers. This link between revenge and justice also explains why, in III.xii, and IV.i, Hieronimo decides to revenge Horatio's death himself and why he interprets Bel-Imperia's offer of help as a sign that Heaven favors his decision. Hieronimo may here consider himself the agent of the divine vengeance that a just God must bring against his son's murderers, the man chosen by God to revenge Horatio's death. His act would thus be a service to God and not an usurpation of God's role.
There is, unquestionably, doubt in the audience's mind as to whether Hieronimo is right, and a similar ambiguity is felt toward other cases of revenge in the play as well—Andrea's and Bel-Imperia's, for example. Exactly what deaths should be revenged and who should do the revenging were topical questions for Elizabethans, who were living in a time when the Elizabethan state was bringing a centuries-old tradition of private revenge in England under control. It was also a state whose preachers advised leaving revenge to God, while at the same time describing the horrible revenge God would take on sinners. But the problems posed to us by revenge—and the intense desire for it when we or a loved one is injured by another, especially when the law fails to provide us with redress—is something that can be felt by modern audiences as well.
Not only is revenge a form of justice in the play, it is, ironically enough, an expression of love. Bel-Imperia's love for Andrea leads her to desire revenge against Balthazar; Balthazar revenges himself against Horatio because he loves Bel-Imperia. Bel-Imperia and Hieronimo make the most explicit connection between the two, interpreting the failure to revenge one's loved one as a lack of love. The presupposition that underlies all these actions and words is that love for a murder victim finds its fullest expression in vengeance. In effect, vengeance is an assertion that the loved one is not forgotten. Thus, Andrea's desire for vengeance is understandable as a desire not to be forgotten by those still living, and love and revenge are intertwined in the symbol of the bloody handkerchief, which starts out as a simple memento but ends by becoming, for Hieronimo, a symbol of both the memory of his son and the need to revenge his son's death.
The wheel of fortune was a potent image in Elizabethan iconography. It signified, in the Elizabethan consciousness, the vagaries and constant revolutions of Fortune, from low to high and everywhere in between. Lorenzo makes an allusion to it when he notes that the social-climbing Horatio is, hanged from the trees, "higher" than he ever was in life, and the Viceroy makes explicit reference to it in mourning the loss of his son in Act I (though his mourning is ironic, because it is premature). From Andrea onward, the characters we meet all experience drastic reversals of fortune—the loss of a son, the loss of life, the loss of a lover. This vicarious experience of the precariousness of human happiness—the way, in an instant, it can be changed to misery—is one of the unique pleasures that tragedy affords us: we are allowed to experience this loss without actually experiencing the tragic loss ourselves.
Kyd uses dramatic irony throughout the play to drive a wedge between the world as his main characters see it and the world as it actually is. Balthazar and Bel-Imperia see their evening rendezvous in the orchard as a safe space in which to express their love, because Bel-Imperia thinks that Pedringano is a trustworthy servant. In fact, Pedringano is deceitful, and, because of his treachery, the orchard turns into a place of death.
Furthermore, Lorenzo enthusiastically agrees to play his part in Hieronimo's tragedy, not knowing that Hieronimo intends not only his character to die, but for him to die as well. But, perhaps the most concrete and dramatic example of this wedge is Pedringano's belief that a pardon is contained inside the box Lorenzo has sent him. The box then comes to symbolize, in the view of many critics, a more fundamental and general limitation on human knowledge. In other words, the characters' inability to get past appearances is typical of all human beings' inability to penetrate appearances.
Kyd uses many allusions to the classical world. The topography of the underworld he provides is directly taken from Virgil's Aeneid, with some minor modifications. And he borrows many plot conventions and some rhetorical devices—for example, stichomythia, or a dialogue consisting of line-by-line exchange—from the Roman playwright Seneca. He also seems to adopt a pagan idea of revenge and justice: that humans must attempt to find justice for themselves (if they can), because the world full of injustice. There are also indications, however, that Hieronimo considers himself acting on God's behalf in his revenge.
Madness becomes manifested in two distinct persons in the play: Hieronimo and Isabella. The first case of madness eventually leads to bloody revenge, while the second leads to suicide. One turns outward for destruction, and the other seeks it inward. They are, however, both manifestations of a desire to escape from a horrible reality. Interestingly, the cases of madness are paradoxical, because they are a kind of "sane" madness—madness in the face of a world that has itself gone insane and to which madness is the only possible response. This madness places the sane and happy, such as the King, in an ironic position, especially if we understand "madness" as a disconnected state from reality. In the world of the play, it is the sane and happy who are truly disconnected from reality, unable to even see the pervasive evil that surrounds them.
An Elizabethan audience would easily recognize in Lorenzo, the chief antagonist of the play, the influence of Machiavelli, sixteenth-century Italian political philosopher. In Elizabethan England, Machiavelli's name was synonymous with evil. Though undoubtedly its impression of his philosophy was simplistic, Elizabethan England associated Machiavelli with duplicity and use of violence and fear. Machiavelli's philosophy was actually intended for the rulers of cities; he maintained (reasonably) that such rulers could not be bound by conventional morality. The Machiavellian villain however, of which there are many other examples in Elizabethan literature, applied the philosopher's principles to private life. Ironically, Hieronimo, the play's protagonist, is forced to adopt Machiavellian tactics in order to avenge his son.
Both rhetorically and in terms of characterization, Kyd loves opposites: Lorenzo is unequivocally unjust, while Hieronimo is unequivocally just. Horatio is honourable, while Lorenzo is typically dishonourable. This love for opposition expresses itself in the frequent occurrence of the rhetorical device of antithesis, where the opposition of two ideas is expressed in one sentence or in a parallel structure of sentences. But these antithetical structures will often culminate in a final sentence that resolves the differences between the two into an underlying similarity, either through a direct statement of this similarity, such as Balthazar's "I yield myself to both" or through an oxymoron, such as Bel-Imperia's "warring peace."
Similarly, many of the initially antithetical characters at times seem very similar to each other. At the end of the play, Hieronimo adopts Lorenzo's Machiavellianism, and Lorenzo plays Hieronimo's part of the innocent dupe. Because of Lorenzo's plot, the just Hieronimo ends up committing an act of injustice in the hanging of Pedringano. These resolutions and exchanges are ironic, because they show how both meanings and intentions are ambiguous and easily reversed: Bel-Imperia's love is both war and peace; Hieronimo needs to be a villain in order to be a hero and avenge his son; Bel-Imperia's desire to revenge herself on Balthazar by causing him pain ends up causing her intense grief; and the commission of justice can often turn into a commission of injustice (for example, in the case of the hanging of Pedringano). Such ironies pervade the play and help create the double perspective in which we view the action. We are separated from the actions of the characters, especially Hieronimo, by the knowledge that they act in error, but we also empathize with them because of the uncertain situations in which they are forced to act, in which the meaning and intentions of their actions often slip away.
We have, in addition to the play, a character within the play who watches the play's main events and is as isolated from them as we are: Don Andrea. We also have another character, Revenge, who—while separated from the play—seems to be affecting it in spirit and to have a knowledge of what is to come. He uses this knowledge to continually tease Andrea. We see ourselves in a very similar position at times, to both Andrea and Revenge, knowing what is going to happen and then not knowing, isolated from the action and yet identifying with the characters to whom it happens. The existence of this meta-theater thus serves to make the relationship between the play-world and the real world ambiguous; on one hand, we are still separated from the characters by a radical divide (we exist, they do not), but on the other, we exist in a position almost exactly identical to Andrea and Revenge. This ambiguity is played upon and further heightened by Hieronimo's revenge playlet in Act IV.
The handkerchief starts off as a symbol of love and memory, becomes a symbol of the memory of a lost loved one, and then a symbol for the desire to avenge that loved one. Ironically, by the end of the play, it can be seen as a symbol of the need to erase memory through death. Before Andrea went off to war, Bel-Imperia gave him a scarf, which he wore into battle something by which to remember her. Initially a symbol of love between Andrea and Bel-Imperia, Horatio takes it off his friend's dying body as a memorial, and it then becomes a symbol of Horatio's remembrance of his friend, a symbol of love between Horatio and Bel-Imperia, and of Bel-Imperia's memory of her lost knight. Of course, Bel-Imperia's love for Horatio is itself a form of revenge against Balthazar, so the scarf begins to take on connotations of vengeance. After Horatio's death, Hieronimo presumably takes the same handkerchief. It is now a symbol of both love and vengeance, intertwined in Hieronimo's desire to avenge his beloved son. By the end of the play, it becomes a symbol of annihilation and erasure. Hieronimo holds the handkerchief up in the midst of the corpses onstage and then runs off to commit suicide, embracing death and the erasure of all memories.