Guilt can mean both responsibility for a crime and the state of mind produced by committing one. A defendant who loses his case is the guilty party; a thief who escapes the law but is tormented by remorse is guilty in another way. Shakespeare is concerned with the second kind of guilt in Macbeth. Duncan's murder takes place offstage at the end of the first act, too early for it to serve as the play's climax. Instead, the dramatic action focuses on the decisions that Macbeth and Lady Macbeth make, leading up to the murder and its terrible aftermath.
Macbeth first feels guilt while the "murder is yet but fantastical" (1.3.140)—that is to say, at the mere thought of killing the king. He knows, as does Lady Macbeth, that doing so would be a triple transgression: It denies Duncan the loyalty they owe him as subjects, the kindness they owe him as kin, and the protection and hospitality they owe him as hosts. It is important that both Macbeth and Lady Macbeth realize that the murder is morally wrong. If they did not, it would be impossible for them to feel guilty about it afterward.
Macbeth and Lady Macbeth repeatedly voice their desire for the cloak of night to cover their misdeeds: "Stars hide your fires; / Let not light see my black and deep desires" (1.4.50–51). They assume that if no one sees their crime, they cannot be held accountable for the murder. Taking their desire for secrecy a step further, Macbeth commands his eye to "wink at the hand" (1.4.52), and Lady Macbeth hopes the knife will "see not the wound it makes" (1.5.48). Not only do they want to avoid blame—the first kind of guilt—they also want to be ignorant of the crime themselves, in order to escape the second kind, too.
On the night Duncan is killed, the stars do hide from view. But it is an unnatural darkness, a sign that Macbeth and Lady Macbeth have disrupted the natural order of things. Lady Macbeth's plan to frame the guards succeeds in shifting blame for the murder onto them, at least temporarily, but she and Macbeth must still bear alone the spiritual and psychological burden of their guilt.
The effects of Macbeth's guilt appear immediately after the murder. He begins to hallucinate and hear voices. He cannot pray, and he is too fearful and restless to sleep. He feels changed, tainted, by what he has done. He describes his guilt as a stain that he cannot wash off, for it would sooner color the whole world than fade from his skin. He also compares his guilt to a cage, telling his wife: "[N]ow I am cabined, crabbed, confined, bound in / To saucy doubts and fears" (3.4.24–25).
At the banquet, Macbeth's guilty conscience—newly burdened by the assassination of Banquo—produces an even more elaborate hallucination. He sees the ghost of the murdered man in his seat, glaring at him coldly. His nervous and self-incriminating behavior here is the first of several incidents that make the other thanes suspect that he is being driven mad by guilt.
Guilt's effect on Lady Macbeth is delayed but ultimately just as profound. It may begin as early as the morning after Duncan's death, when she collapses upon hearing that the king has been murdered. The reason for Lady Macbeth's collapse, however, is left ambiguous. The play does not make clear whether she has fainted because she finally understands the gravity of what she and Macbeth have done, or whether she has feigned a shocked swoon to deflect suspicion.
By act 5, Lady Macbeth's collapse is total, and there can be no doubt about the fact that it is directly related to Duncan's murder. She cannot bear to be without a light at all times; having once wished for the obscurity of darkness, she now tries to keep the night and the things that it hides at bay. Like Macbeth, she feels tainted by the murder, and she compulsively washes her hands in a vain effort to be clean and, therefore, innocent. Also like Macbeth, she is denied the balm of sleep: In her waking nightmares, she speaks in prose rather than blank verse—her speech, like her nerves, is in tatters. The Doctor declares her more in need of a priest than a physician, remarking, "Unnatural deeds do breed unnatural troubles" (5.1.58–59). By the end of the act, Lady Macbeth is dead, possibly by her own hand and certainly as a result of her tortured conscience.
Text Citation (Chicago Manual of Style format): Nelson, Cassandra. "guilt in Macbeth." McClinton-Temple, Jennifer ed. Encyclopedia of Themes in Literature. New York: Infobase Publishing, 2011. Bloom's Literary Reference Online. Facts On File, Inc. http://www.fofweb.com/activelink2.asp?ItemID=WE54&SID=5&iPin= ETL1000&SingleRecord=True (accessed March 4, 2013).