After the bloody imagery and dark tone of the previous two scenes, the porter's comedy comes as a jarring change of tone. His good-natured joking with Macduff breaks up the mounting tension of the play and also comments obliquely on its themes. Unlike all the characters of noble birth, who speak in iambic verse, the porter speaks in prose. His relaxed language seems to signal that his words and his role are less important than those of the other characters, but in his merry banter the porter hits on many truths. His description of the confusion and lust provoked by alcohol caricatures Macbeth's moral confusion and lust for power. Moreover, his remarks about the ineffective lechery inspired by drink eerily echo Lady Macbeth's sexual taunting of Macbeth about his ability to carry out his resolutions. The porter's joke that the door of Inverness is like hell's gate is ironic, given the cruel and bloody events that are taking place within the castle. When he cries, "Who's there, i' th' name of Beelzebub [the devil]?" the analogy between hell and Inverness becomes even stronger (2.3.3). Instead of receiving a welcome and a blessing when they step into Macbeth's castle, guests are warned that they are putting themselves in the hands of the devil.
Now that Lady Macbeth's machinations have wrought their result, Lady Macbeth begins to recede from center stage and Macbeth takes her place as the most compelling character in the play. The clipped, halting sentences with which Macbeth speaks to Macduff and Lennox indicate his troubled mind and trepidation about the impending discovery of Duncan's body. For example, while Lennox offers a lengthy speech about the wild weather of the previous night, Macbeth's only response is a terse " 'Twas a rough night" (2.3.57). And when Lennox asks Macbeth, "Goes the King hence today?" Macbeth almost gives away his knowledge that Duncan is dead (2.3.49). "He does," answers Macbeth, before he realizes that his answer is incriminating and changes it to: "[H]e did appoint so" (2.3.49).
Once Duncan's body is discovered, it is as though a switch has been flipped within Macbeth. He springs into action with a clear eye toward his purpose, seizing control of the nobles and becoming King of Scotland. Interestingly, Shakespeare does not show us the scene in which Macbeth is made king. Just as he denied us the scene of Duncan's murder, he now skips over its most direct consequence, Macbeth's election. The news is conveyed secondhand through the characters of Ross, Macduff, and the old man.
Although Macbeth seems to gain confidence as Act 2, scene 3, progresses, other characters subtly cast suspicion on him. When Malcolm asks about his father's killer, Lennox replies, "Those of his chamber, as it seemed, had done't" (2.3.98). Lennox's insertion of "as it seemed" highlights the suspect nature of the crime scene's appearance. Banquo, also, expresses his wariness of Macbeth's argument that the chamberlains were the murderers. He says: "let us meet / And question this most bloody piece of work, / To know it further" (2.3.123–125). By far, though, the most distrusting character is Macduff, who, up until this point in the play, has been a fairly unobtrusive character. He asks Macbeth why he killed the chamberlains, and later expresses his suspicion to Ross and the old man. His decision to return home to Fife rather than travel to Scone to see Macbeth's coronation is an open display of opposition. Thus, in a few swift strokes, the play establishes Macduff as Macbeth's eventual nemesis. Malcolm, of course, is the rightful king, but he lacks Macduff's initiative and sense of purpose, a fact illustrated by his willingness to flee rather than assert his royal rights. In order to regain the throne, he will need the aid of the more assertive Macduff—and it is Macduff, not Malcolm, who assumes the responsibility for Macbeth's death.
The conversation between Ross and the old man at the beginning of Act 2, scene 4, tells the audience about a number of unnatural occurrences in the weather and the behavior of animals, which cast a menacing shadow over Macbeth's ascension to the throne. In Shakespeare's tragedies (Julius Caesar, King Lear, and Hamlet, in particular), terrible supernatural occurrences often betoken wicked behavior on the part of the characters and tragic consequences for the state. The storms that accompany the witches' appearances and Duncan's murder are more than mere atmospheric disturbances; they are symbols of the connection between moral, natural, and political developments in the universe of Shakespeare's plays. By killing Duncan, Macbeth unleashes a kind of primal chaos upon the realm of Scotland, in which the old order of benevolent king and loyal subjects is replaced by a darker relationship between a tyrant and his victims.
