DAVINA: I think this scene is a great example of how Shakespeare functions on three different levels: Shakespeare the dramatist, Shakespeare the philosopher, and Shakespeare the poet. 
RALPH: I couldn’t agree more, Davina. As a dramatist Shakespeare tells a great story. After considering the arguments against killing Duncan, Macbeth decides to proceed no further. But Lady Macbeth relentlessly pressures him, attacking his manhood. They can’t fail if only he can muster some courage and follow the plan she has concocted. She has won him back over.
DAVINA: It’s Shakespeare the philosopher who shows us the thought process of a man debating whether to commit a morally reprehensible act, motivated solely by his vaunting political ambition. What are the consequences that make him reconsider – retribution in this world, or eternal damnation in the afterlife?
RALPH: Then there’s the issue of agency. Even if there are no Greek goddesses controlling our destiny, might not external suggestions trigger impulses buried deep in our psyche, and spur us to perform deeds that we would not otherwise have done? 
DAVINA: And being so strongly bound in a relationship with someone like Lady Macbeth, is Macbeth 100% responsible for being caught up in this nefarious plot?
RALPH: Finally we have Shakespeare the poet, using heavenly imagery and metaphors to paint a dramatic picture of a virtuous Duncan’s death. It’s dramatically striking that it’s Macbeth, the plotter of the murder, that uses this precise poetic language, indicating that he fully understands the wickedness of the deed he is contemplating.