Context:
Banquo was believed to be an ancient relative of James I. James was Shakespeare's patron, having taken on sponsorship of Shakespeare's acting company, renamed The King's Men. So it was in Shakespeare's interest to paint James' ancestors in a good light: Banquo is presented as resisting the temptation of the witches and remaining solidly loyal to Duncan. Even beyond the grave Banquo continues to work for the truth, returning as a vengeful ghost to trouble Macbeth's conscience and force him to admit what he has done. |