1. Introduction

The complexity of the tyrant’s psychology as reflected in Shakespeare’s play Macbeth has long attracted the attention of scholars, and the analysis about the witches and Lady Macbeth mainly focuses on the external influence of witches as supernatural elements and Lady Macbeth as a seducer on Macbeth’s psychology. A.C. Bradley, for instance, notes that the Witches’ prophecies foreshadow the future without imposing inevitability, prompting reflection on “how far his mind [is] guilty”. [1] Marina Favella further illuminates the duality of Macbeth’s inner self. Based on the Oedipus complex mentioned by Sigmund Freud, she believes that Macbeth’s spiritual world is divided into two parts of desire and conscience which “[t]he former attempts to control the world with magical thinking; the latter attempts to control the self through ethical thinking”. [2] Such an opinion challenges the notion of Macbeth’s one-sided dependence on his lady. Gender-analytic critics such as Mehdi Amiri and Sara Khoshkam have dissected the play’s exploration of masculinity and lack of motherhood, arguing that “[w]hat presents itself in this play is a conflation of sex parts and of gender”, further breaking down the gender limitations in interpreting Macbeth’s relationship with the witches and Lady Macbeth, turning Macbeth’s one-way dependence into interaction between characters [3]. Through these studies, in recent years, the academic circle has mostly regarded desire as the driving force of this tragedy and focused on Lady Macbeth’s subjectivity from the perspective of maternal anxiety and gender performance under the patriarchal framework. These perspectives, however, ignore the alienating logic of desire itself, Macbeth’s subjective initiative, and the structural symbiotic relationship between the characters’ psychological frameworks. This paper analyses the metaphor of witches in the play and compares the psychological development of Macbeth and Lady Macbeth in the three murders, constructing the “parasite-host” relationship between Macbeth and Lady Macbeth, thus arguing the formation of Macbeth’s tyrannical personality is a psychological outsourcing process manipulated by Macbeth himself.

2. The externalization of desire: from Witches’ prophecy to parasitic strategy

Macbeth opens with an ambiguous and prophetic encounter that the weird witches greet Macbeth with prophecies of kingship. The witches’ appearance coincides with Macbeth’s victory over MacDonald’s rebellion. Their opening dialogue “[w]hen the hurly-burly’s done” (1.1.3) and “[w]hen the battle’s lost and won” (1.1.4)—establishes a temporal link between chaos and revelation [4]. When Macbeth returns victorious and has the strength and honor to further seize the throne, they honor Macbeth as “Thane of Glamis”, “Thane of Cawdor”, and “the king hereafter”. This temporal consistency suggests that the weird witches are not so much an external supernatural influence as the voice of Macbeth’s already existing desires deep in his heart, and a psychological projection of Macbeth’s potential desire for greater power. His urgent response—“[s]tay, you imperfect speakers, tell me more!”(1.3.70)—is not an expression of shock at the prophecy’s transgressive content, but a desire to have his unspoken wishes confirmed. As Emilian Tîrban noticed, “[t]he initial meeting between Macbeth and the Witches questions the possibility that the witches’ prophecies are projections of the protagonist’s repressed ambitions”. [5] This externalized desire immediately conflicts with Macbeth’s inner moral constraints which is reflected in his soliloquy:

My thought, whose murther yet is but fantastical,

Shakes so my single state of man,

That function is smother’d in surmise,

And nothing is, but what is not.

(1.3.141-144)

According to Ahmet Süner, the supernatural form of the witches let them “occupy a curious ontological position between human and non-human”. [6] This ontological liminality structurally mirrors Macbeth’s own psychological split: just as the witches exist betwixt human and non-human, Macbeth’s psyche oscillates between his desire and morality. On the one hand, Macbeth’s nature is “full o’th’ milk of human kindness” (1.5.17) which prevent him from using despicable means to seize the throne; on the other hand, the desire tempts him so strongly that he cannot ignore it or even completely reject it. The contradiction between the two constitutes a mental split that Macbeth cannot reconcile himself with, renders him incapable of translating fantasy into action independently.

To circumvent his moral inhibitions and motivate himself to take actions, he chooses to externalize his desire for personality and parasitize it on his wife through his letter about witches’ prophecies, which leads to Lady Macbeth’s invocation to “unsex” (1.5.41) herself. Cristina León Alfar defines Lady Macbeth’s desire as “an ideologically inscribed notion”. [7] By “[c]alling on unholy spirits” to strip away the female attribute inherent in her own personality, she transforms herself into a spectral embodiment of ideological desire and pours “[her] spirits” (1.5.26) in Macbeth’s ear [2]. While she appears to dominate their dynamic, it is Macbeth’s letter that “inscribes” this violent ideal into her consciousness. Through such “parasitism”, the desire personality replaces Lady Macbeth’s original personality, thereby manipulating her to unsex herself to serve the realization of Macbeth’s desire. This process aligns with Jacques Lacan’s concept of the “mirror phase,” in which the subject assumes an idealized image projected onto others [8]. Macbeth parasitizes his imaginary kingship on Lady Macbeth, allowing her to construct and nourish his own tyrannical mirror-image until it develops into a strong will to kill King Duncan and feeds it to Macbeth by “take[ing] [her]milk for gall” (1.5.48) like a “host”, thus enabling Macbeth, as a passive actor, to avoid the moral condemnation of active regicide and motivate the fusion of himself with the personality of desire.

3. The first manifestation for parasitic relationships: from illusion to regicide

The process by which Lady Macbeth as the host feeds the “nutrient” of desire personality to Macbeth as the parasite is reflected in the psychological portrayal of both within the three murder scenes of the play. The first occurs in Act 2, Scene 1, where Macbeth’s soliloquy reveals his acute internal conflict during the difficult “passage from thought to critical resolution and action”, and the phrase “the one half world” (2.1.49) provides a crucial insight into Macbeth’s split psyche [1]. At that moment, Macbeth seems to be living in two distinct worlds corresponded to his inner split of morality and desire: one is the internal, illusory dream world in which “nature seems dead”(2.1.50); the other is the external, tangible real world where actions and consequences manifest. Two recurring images in this scene—the dagger and the bell—embody the transference of desire from Lady Macbeth to Macbeth.

The vision of the dagger is a direct expression of Macbeth’s inner struggle, which many scholars interpret as a supernatural projection of his psychological fears. According to Marguerite A. Tassi, the dagger is phenomenologically “a visible object of horror” “from [his] heat-oppressed brain” (2.1.39) [9]. Ahmet Süner further argues that the image of dagger is “more of the horrifying nature of human thought than of any repressed desires that cause guilt”. [6] However, as Bradley suggests, no “external power” is forced on Macbeth to do anything [1]. Macbeth sees the handle pointing toward him, yet whether “clutch” (2.1.34) it or not depends on himself. In this scene, Macbeth questions the existence of the dagger three times, and each time the question is sharper than the last. Yet Macbeth always tries to rationalize the existence of the dagger by repeating affirmations in a self-hypnotic way—he repeats “I see thee” three times correspondingly and the dagger becomes more and more specific and detailed, from “fatal vision” (2.1.36) to “form as palpable” (2.1.40) and finally he can even feel “gouts of blood” (2.1.46) on the dudgeon. The dagger persists because Macbeth wills it, serving as a physical manifestation of his desire. He tries to separate his desire into a concrete object like the dagger, disguise his desire as the effects of the external, and thus externalize his inner desire. As is mentioned before, Macbeth is still unable to break free from the self-restraints of morality. No matter how he hypnotizes himself, he cannot make the leap from fantasy to reality independently. Therefore, Macbeth needs to rely on Lady Macbeth, who is parasitized by his desires, to promote his first leap from imagination to action.

Unlike the insubstantial image of the dagger, the bell is concrete, audible, and universally perceptible. It is a tangible summons that crosses the boundary between the internal and external worlds. We can find that, although Macbeth’s inner “one half world” has been occupied by unnatural desires, it does not affect the other real “one half world” that is still natural until the bell rings. Tassi interprets Macbeth’s ghostlike movement (2.1.56) as “a metamorphosis from material to immaterial”. [9] However, Macbeth then says “[hear] not my steps” (2.1.57). In other words, he is still unable to face the real impact of his inner desire on the real world and remains in the immaterial world from the beginning. Thus, Lady Macbeth’s bell becomes a medium through which Macbeth’s inner desire is translated into concrete action in the real world. Thus, Macbeth relies on Lady Macbeth’s bell as a medium to break the boundary between the illusion and the reality, catalyses the irreversible act of regicide and makes himself merge with the tyrant’s personality at the action level.

4. The erosion of host function: Macbeth’s transformation from parasite to tyrant

Macbeth’s murder of Banquo marks the second pivotal shift in his parasitic dynamic with Lady Macbeth. Unlike Duncan’s murder—a meticulously co-authored crime led by Lady Macbeth—this killing is Macbeth’s unilateral decision. He neither consults his wife nor reveals his plan to her and declares in his soliloquy:

For Banquo’s issue have I fil’d my mind;

For them the gracious Duncan have I murther’d;

Put rancours in the vessel of my peace,

Only for them; and mine eternal jewel

Given to the common Enemy of man, […]

(3.1.64-68)

This solipsistic rhetoric reveals his growing autonomy: the “host” is no longer a necessary condition to take actions. Yet, his moral disintegration remains incomplete. By guiding the murderers with instructive language to share his hatred for Banquo, Macbeth replicates his strategy of outsourcing, and transforms the murderers into his own agents. Although the decision to murder Banquo is made by him, he still cannot directly face his own desires. The act is paradoxically both autonomous and evasive — he claims agency while perpetuating psychological displacement. At this moment, Lady Macbeth’s function is reduced from a catalyst for action to a psychological comforter. Through her words, she further enables Macbeth to abandon his moral obstacles “which should indeed have died” (3.2.11).

The banquet scene in Act 3 Scene 4 crystallizes Macbeth’s unresolved moral dilemma. The ghost of Banquo, as a physical manifestation of Macbeth’s moral residue, forces him to confront the very conscience he sought to outsource. Macbeth’s cry—“[t]hou canst not say I did it!” (3.4.47)—is less a denial of guilt than a rejection of personal responsibility. Yet crucially, this confrontation becomes a catalyst for his transformation. When the ghost vanishes, Macbeth’s resolve hardens:

Stepp’d in so far, that, should I wade no more,

Returning were as tedious as go o’er.

Strange things I have in head, that will to hand,

Which must be acted, ere they may be scann’d.

(3.4.135-138)

This metaphorical “wading” indicates the complete unity of his original superego and desire personality that he no longer needs Lady Macbeth to comfort his psyche. Seth L. Schein demonstrates that from this point on “‘tyrant’ and ‘tyranny’ are used frequently to describe Macbeth and his evil way of ruling and to justify his violent overthrow”. [10] Meanwhile, Lady Macbeth’s diminished effectiveness is evident after the banquet. Her pleading stands in stark contrast to her earlier guidance of Macbeth’s behaviour. At this point, Lady Macbeth has lost all her functions as a host, and Macbeth, after achieving the leap between the two worlds, further eliminates moral barriers and becomes a complete tyrant.

Macbeth’s killing of Macduff’s family epitomizes the end of his parasitic dependency on Lady Macbeth. On the one hand, Macbeth claims that he will see “no more sights” (4.1.154) and expands his scope of murder to Macduff’s family members who pose no threat to his kingship. As the murder turns into a collective massacre, it marks the complete loss of control of Macbeth’s tyrannical personality. On the other hand, Lady Macbeth’s irrelevance is tragically mirrored in her madness. Joanna Levin argues that “Lady Macbeth combines aspects of the witch and the mother figure in patriarchy into an uneasy fusion”. [11] However, although she defines Lady Macbeth’s identity as a “Mother”, the stagnation and emptiness displayed by Lady Macbeth at this time provide us with another interpretation. Her lines under her manic state focus on Duncan’s blood and Banquo’s ghost but does not mention Macduff’s family. This selective guilt confirms that she has been excluded from Macbeth’s calculations, and her consciousness stops at the timeline of the murder of Banquo. Since Lady Macbeth’s original personality as the host is parasitized and replaced by Macbeth’s desire personality, Lady Macbeth fatally becomes an empty shell that is of no use to Macbeth when Macbeth as the parasite has obtained enough nutrients from the host to complete the transfer to grow into a tyrant. This is also the reason why Macbeth said “[s]he should have died hereafter” (5.5.16). Macbeth naturally shows indifference towards Lady Macbeth’s death as the parasite has no feelings for the host. With the end of the parasitic relationship, Lady Macbeth’s death is not a hysterical self-collapse, but the inevitable death of the host abandoned by the parasite.

5. Conclusion

Shakespeare’s Macbeth is ultimately not a tragedy of supernatural manipulation but an analysis of how desire degenerates people into alienated forms. Through analyzing the progressive development of Macbeth’s tyrannical expression in three murders and the gradual separation and exit of Lady Macbeth, this article reveals that Macbeth’s tyranny does not originate from external forces but from a carefully planned process of parasitic externalization. In this parasitic framework, the witches are the projection of Macbeth’s latent ambitions, while Lady Macbeth is the host of his moral degradation. They serve as Macbeth’s externalized images and auxiliary tools of his desire. The real horror of the play lies not in regicide or madness, but in the systematic dehumanization caused by individuals who do whatever it takes to circumvent moral condemnation to fulfil their desires, and Lady Macbeth’s empty soul and Macbeth’s ultimate loss of control embody the annihilation of subjectivity in this process. Macbeth’s tragedy lies not in the mere possession of desires but in his active authorship of their alienating power, which reduces him to a slave of primitive instinct. Shakespeare’s critique thus transcends individual morality, condemning desire itself as a force that dehumanizes, reducing humanity to creatures governed by base impulses. However, the current study mainly focuses on the internal logic of the text, and it can be combined with other Shakespeare’s works and historical backgrounds to deepen the analysis. At the same time, whether this theoretical model can explain other types of power alienation of Shakespeare’s tyrannical figures still needs more exploration.