As you read Act 4, consider the role of the witches. They open this scene and remind us all of the power they wield:
Double, double, toil and trouble; /Fire burn and cauldron bubble….
By the pricking of my thumbs,/ Something wicked this way comes…
That ‘something wicked’ is Macbeth. Consider, too, the changes in Macbeth. Now, as king, he demands: ‘Answer me’. He is pleased by their equivocations (he interprets them as predictions in his favour) and acknowledges that they have guessed his fear when they warn him of Macduff. As he watches the apparitions he is led to feel pleased: ‘Sweet bodements!/good!) but can’t help give voice to his nagging fear that his actions might all be for Banquo’s issue. He asks a direct question and is shown the line of eight kings – he is in disbelief. This is a moment of realisation. It is to Lennox that he communicates his change in his attitude towards them: ‘Infected be the air whereon they ride, / And damn’d all those that trust them!’ The audience understand the irony and the action to come plays out the foreshadowing in this scene.
Throughout Act 4 there are many references to blood and bloodshed and it is clear that nature is rebelling agains the unnatural reign of Macbeth. Malcolm’s admission:
‘I think our country sinks beneath the yoke; It weeps, it bleeds, and each new day a gash/Is added to her wounds’
This is a cry for the tyranny and violence to end. The climax of the action in this act is undoubtedly the onstage killing (remember that Duncan’s was off stage) of Macduff’s family.
Act 4 closes with the resolution that Macbeth must be stopped. Macduff is overcome with grief but receives this advice from Malcolm: ‘Be this the whetstone of your sword: let grief/Convert to anger; blunt no the heart but enrage it.’ The audience is prepared for the play’s final act and the downfall of Macbeth.