RALPH: Now we come to the strongest argument against murdering Duncan: he’s a good king. As Macbeth acknowledges, Duncan has been a humble ruler, and he has carried out the powers of his office in a just and ethical fashion. 

DAVINA: This is a strong moral argument against the murder, and Shakespeare makes this point with some wonderful imagery evoking a medieval religious painting. Duncan’s virtues are like trumpet-playing angels pleading his case.

RALPH: And if Duncan were killed, people’s pity for him would ride the blast of air coming out of the trumpets, causing everyone to cry.

DAVINA: The offense would provoke such anguish in people that their tears would “drown the wind”, just as the sudden downfall of heavy rain can stop the wind in a storm.

RALPH: With this imagery, Shakespeare oddly mixes sound and visual metaphors - pity steers the sound of trumpet blasts into the eyes of the people, so they can see the murder for what it is.

DAVINA: That’s interesting, Ralph. Most English teachers would criticize a student for mixing metaphors like this, but with Shakespeare, it seems to work.

RALPH: Macbeth sums up his thoughts: There is no spur, no strong argument, that would impel Macbeth to murder the king; his only motivation is his ‘vaulting’ ambition for power.

DAVINA: Once again, notice the riding metaphors – “no spur to prick the side of my intent,” like a rider spurring a horse, and ‘to vault’ means to leap up into the saddle.

RALPH: Just as his wife enters, Macbeth concludes his argument by extending the metaphor of horseback riding: instead of landing in the saddle of kingship, his vaulting ambition would land him on the other side of the horse entirely.