In a dark cavern, a bubbling cauldron hisses and spits, and the three witches suddenly appear onstage. They circle the cauldron, chanting spells and adding bizarre ingredients to their stew—“eye of newt and toe of frog, / Wool of bat and tongue of dog” (IV.i.14–15). Hecate materializes and compliments the witches on their work. One of the witches then chants: “By the pricking of my thumbs, / Something wicked this way comes” (IV.i.61–62). In fulfillment of the witch’s prediction, Macbeth enters. He asks the witches to reveal the truth of their prophecies to him. To answer his questions, they summon horrible apparitions, each of which offers a prediction to allay Macbeth’s fears. First, a floating head warns him to beware Macduff; Macbeth says that he has already guessed as much. Then a bloody child appears and tells him that “none of woman born / shall harm Macbeth” (IV.i.96–97). Next, a crowned child holding a tree tells him that he is safe until Birnam Wood moves to Dunsinane Hill. Finally, a procession of eight crowned kings walks by, the last carrying a mirror. Banquo’s ghost walks at the end of the line. Macbeth demands to know the meaning of this final vision, but the witches perform a mad dance and then vanish. Lennox enters and tells Macbeth that Macduff has fled to England. Macbeth resolves to send murderers to capture Macduff’s castle and to kill Macduff’s wife and children.

At Macduff’s castle, Lady Macduff accosts Ross, demanding to know why her husband has fled. She feels betrayed. Ross insists that she trust her husband’s judgment and then regretfully departs. Once he is gone, Lady Macduff tells her son that his father is dead, but the little boy perceptively argues that he is not. Suddenly, a messenger hurries in, warning Lady Macduff that she is in danger and urging her to flee. Lady Macduff protests, arguing that she has done no wrong. A group of murderers then enters. When one of them denounces Macduff, Macduff’s son calls the murderer a liar, and the murderer stabs him. Lady Macduff turns and runs, and the pack of killers chases after her.

Outside King Edward’s palace, Malcolm speaks with Macduff, telling him that he does not trust him since he has left his family in Scotland and may be secretly working for Macbeth. To determine whether Macduff is trustworthy, Malcolm rambles on about his own vices. He admits that he wonders whether he is fit to be king, since he claims to be lustful, greedy, and violent. At first, Macduff politely disagrees with his future king, but eventually Macduff cannot keep himself from crying out, “O Scotland, Scotland!” (IV.iii.101). Macduff’s loyalty to Scotland leads him to agree that Malcolm is not fit to govern Scotland and perhaps not even to live. In giving voice to his disparagement, Macduff has passed Malcolm’s test of loyalty. Malcolm then retracts the lies he has put forth about his supposed shortcomings and embraces Macduff as an ally. A doctor appears briefly and mentions that a “crew of wretched souls” waits for King Edward so they may be cured (IV.iii.142). When the doctor leaves, Malcolm explains to Macduff that King Edward has a miraculous power to cure disease.

Ross enters. He has just arrived from Scotland, and tells Macduff that his wife and children are well. He urges Malcolm to return to his country, listing the woes that have befallen Scotland since Macbeth took the crown. Malcolm says that he will return with ten thousand soldiers lent him by the English king. Then, breaking down, Ross confesses to Macduff that Macbeth has murdered his wife and children. Macduff is crushed with grief. Malcolm urges him to turn his grief to anger, and Macduff assures him that he will inflict revenge upon Macbeth.

The witches are vaguely absurd figures, with their rhymes and beards and capering, but they are also clearly sinister, possessing a great deal of power over events. Are they simply independent agents playing mischievously and cruelly with human events? Or are the “weird sisters” agents of fate, betokening the inevitable? The word “weird” descends etymologically from the Anglo-Saxon word “wyrd,” which means “fate” or “doom,” and the three witches bear a striking resemblance to the Fates, female characters in both Norse and Greek mythology. Perhaps their prophecies are constructed to wreak havoc in the minds of the hearers, so that they become self-fulfilling. It is doubtful, for instance, that Macbeth would have killed Duncan if not for his meeting with the witches. On the other hand, the sisters’ prophecies may be accurate readings of the future. After all, when Birnam Wood comes to Dunsinane at the play’s end, the soldiers bearing the branches have not heard of the prophecy.

Whatever the nature of the witches’ prophecies, their sheer inscrutability is as important as any reading of their motivations and natures. The witches stand outside the limits of human comprehension. They seem to represent the part of human beings in which ambition and sin originate—an incomprehensible and unconscious part of the human psyche. In this sense, they almost seem to belong to a Christian framework, as supernatural embodiments of the Christian concept of original sin. Indeed, many critics have argued that Macbeth, a remarkably simple story of temptation, fall, and retribution, is the most explicitly Christian of Shakespeare’s great tragedies. If so, however, it is a dark Christianity, one more concerned with the bloody consequences of sin than with grace or divine love. Perhaps it would be better to say that Macbeth is the most orderly and just of the tragedies, insofar as evil deeds lead first to psychological torment and then to destruction. The nihilism of King Lear, in which the very idea of divine justice seems laughable, is absent in Macbeth—divine justice, whether Christian or not, is a palpable force hounding Macbeth toward his inevitable end.

The witches’ prophecies allow Macbeth, whose sense of doom is mounting, to tell himself that everything may yet be well. For the audience, which lacks Macbeth’s misguided confidence, the strange apparitions act as symbols that foreshadow the way the prophecies will be fulfilled. The armored head suggests war or rebellion, a telling image when connected to the apparition’s warning about Macduff. The bloody child obliquely refers to Macduff’s birth by cesarean section—he is not “of woman born”—attaching a clear irony to a comment that Macbeth takes at face value. The crowned child is Malcolm. He carries a tree, just as his soldiers will later carry tree branches from Birnam Wood to Dunsinane. Finally, the procession of kings reveals the future line of kings, all descended from Banquo. Some of those kings carry two balls and three scepters, the royal insignia of Great Britain—alluding to the fact that James I, Shakespeare’s patron, claimed descent from the historical Banquo. The mirror carried by the last figure may have been meant to reflect King James, sitting in the audience, to himself.

The murder of Lady Macduff and her young son in Act IV, scene ii, marks the moment in which Macbeth descends into utter madness, killing neither for political gain nor to silence an enemy, but simply out of a furious desire to do harm. As Malcolm and Macduff reason in Act IV, scene iii, Macbeth’s is the worst possible method of kingship. It is a political approach without moral legitimacy because it is not founded on loyalty to the state. Their conversation reflects an important theme in the play—the nature of true kingship, which is embodied by Duncan and King Edward, as opposed to the tyranny of Macbeth. In the end, a true king seems to be one motivated by love of his kingdom more than by pure self-interest. In a sense, both Malcolm and Macduff share this virtue—the love they hold for Scotland unites them in opposition to Macbeth, and grants their attempt to seize power a moral legitimacy that Macbeth’s lacked.

Macduff and Malcolm are allies, but Macduff also serves as a teacher to Malcolm. Malcolm believes himself to be crafty and intuitive, as his test of Macduff shows. Yet, he has a perverted idea of manhood that is in line with Macbeth’s. When Ross brings word of Lady Macduff’s murder, Malcolm tells Macduff: “Dispute it like a man” (IV.iii.221). Macduff answers, “I shall do so, / But I must also feel it as a man” (IV.iii.222–223). Macduff shows that manhood is comprised of more than aggression and murder; allowing oneself to be sensitive and to feel grief is also necessary. This is an important lesson for Malcolm to learn if he is to be a judicious, honest, and compassionate king. When, in Act V, scene xi, Malcolm voices his sorrow for Siward’s son, he demonstrates that he has taken Macduff’s instruction to heart.