What are the forces that lead to the murder of Duncan?
In my opinion, there are three main forces which lead Macbeth to murder King Duncan. These include the witches' predictions, the influence of Lady Macbeth, and Macbeth's own free will. The witches (or the "weird sisters" as they are sometimes called) are the first of these three forces to affect Macbeth. Macbeth and his friend Banquo are walking when they encounter the three witches. Macbeth encourages the witches to speak and they greet him three times. The first witch says, "All hail, Macbeth! hail to thee, Thane of Glamis!" (I. iii 50) At this time in the play, Macbeth's title is Thane of Glamis, so by greeting him as such, they have not yet offered any predictions into the future. However the second greeting does offer a prediction. The second witch says, "All hail Macbeth! hail to thee, Thane of Cawdor!" (I. iii. 51-52) The third witch continues to look into the future when she says, "All hail, Macbeth, that shalt be King hereafter!" (I. iii. 54) Macbeth is not the Thane of Cawdor, nor the King, so he is startled by these prophecies. A short while later, two men ride up and tell Macbeth that he has been given the title of Thane of ...
In my opinion there are three forces which contributed to the murder of King Duncan in Shakespeare's play, "Macbeth". This answer will list these three forces and provide quotes and explanations for each force.