Macbeth
Witchcraft and evil

In the play, the Three Witches represent darkness, chaos, and conflict, while their role is as agents and witnesses. Their presence communicates treason and impending doom. During Shakespeare's day, witches were seen as worse than rebels, "the most notorious traytor and rebell that can be". They were not only political traitors, but spiritual traitors as well. Much of the confusion that springs from them comes from their ability to straddle the play's borders between reality and the supernatural. They are so deeply entrenched in both worlds that it is unclear whether they control fate, or whether they are merely its agents. They defy logic, not being subject to the rules of the real world. The witches' lines in the first act: "Fair is foul, and foul is fair: Hover through the fog and filthy air" are often said to set the tone for the rest of the play by establishing a sense of confusion. Indeed, the play is filled with situations where evil is depicted as good, while good is rendered evil. The line "Double, double toil and trouble," communicates the witches' intent clearly: they seek only trouble for the mortals around them. The witches' spells are remarkably similar to the spells of the witch Medusa in Anthony Munday's play Fidele and Fortunio published in 1584, and Shakespeare may have been influenced by these.

While the witches do not tell Macbeth directly to kill King Duncan, they use a subtle form of temptation when they tell Macbeth that he is destined to be king. By placing this thought in his mind, they effectively guide him on the path to his own destruction. This follows the pattern of temptation used at the time of Shakespeare. First, they argued, a thought is put in a man's mind, then the person may either indulge in the thought or reject it. Macbeth indulges in it, while Banquo rejects.

According to J. A. Bryant Jr., Macbeth also makes use of Biblical parallels, notably between King Duncan's murder and the murder of Christ:

No matter how one looks at it, whether as history or as tragedy, Macbeth is distinctively Christian. One may simply count the Biblical allusions as Richmond Noble has done; one may go further and study the parallels between Shakespeare's story and the Old Testament stories of Saul and Jezebel as Miss Jane H. Jack has done; or one may examine with W. C. Curry the progressive degeneration of Macbeth from the point of view of medieval theology.
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