"Fair is foul, and foul is fair,"

Fair is foul and foul is fair is one of the most famous lines in Shakesphere's plays, in fact, it foreshadows events to come in Macbeth. With these words, they are predicting the evil that will cloud Macbeth's judgments and that those judgments will appear to Macbeth as fair and just but are really foul and wrong. Through his eyes, it is necessary to kill Banquo and several others in this play to withhold his power. In reality none of these people are really threats. The only motive that could have possibly driven Macbeth to kill Banquo is when he looks in the mirror and sees several kings with Banquo’s face, but by this time he had already been murdered.