Under him,
My Genius is rebuked; as, it is said,
Mark Antony’s was by Caesar. He chid the sisters
When first they put the name of king upon me
And bade them speak to him.
– William Shakespeare
Macbeth, Act 3, Scene 1. The paranoid Macbeth wants Banquo killed for a number of reasons. While seeing Banquo as a threat to his crown, Macbeth also believes that his “Genius is rebuked” by Banquo. He recalls that when the Witches first said Macbeth would be king, Banquo chided the Witches and bade them speak to him. In historical terms Macbeth sees himself as Mark Antony, who in the battle for power was eventually defeated by Octavius Caesar. Macbeth fears that Banquo will do a Caesar on him, so he has to be eliminated.