1. The Witches' Prophecies: After Macbeth becomes king, he visits the witches again, and they deliver a series of prophecies. Among them is the warning that he should beware of Macduff, the Thane of Fife, who will eventually overthrow him. This prophecy fills Macbeth with fear and insecurity, making him determined to eliminate Macduff as a potential threat to his power.
2. Macduff's Defiance: Macduff is one of the few noblemen who openly defy Macbeth's tyranny and refuse to support him. He joins forces with Malcolm, the rightful heir to the throne, and becomes a prominent leader of the rebellion against Macbeth. Macduff's defiance further inflames Macbeth's anger and determination to crush his opposition.
3. The Prophecy of the Moving Forest: In the witches' second apparition, they show Macbeth a vision of Birnam Wood marching towards Dunsinane Castle. The witches declare that Macbeth will be safe until Birnam Wood comes to Dunsinane. However, Macduff later leads the rebel forces, cutting down branches from Birnam Wood and carrying them as camouflage to disguise their approach to the castle. This fulfillment of the prophecy triggers Macbeth's realization that his downfall is inevitable, making him even more desperate to kill Macduff.
4. Macbeth's Paranoia and Guilt: Macbeth's guilt over his crimes, particularly the murder of King Duncan, has led him to become increasingly paranoid and ruthless. He sees Macduff as a symbol of his own vulnerability and the potential for retribution. By killing Macduff, Macbeth believes he can secure his position and quell his inner turmoil.
5. Superstitious Belief: Macbeth places a great deal of faith in the witches' prophecies and believes they hold the power to determine his fate. He becomes obsessed with fulfilling them, even if it means committing further acts of violence and murder. This superstitious belief drives him to pursue Macduff relentlessly, convinced that his own safety depends on eliminating this perceived threat.
Ultimately, Macbeth's determination to kill Macduff is a manifestation of his fear, insecurity, and desperation to maintain his power. It highlights the destructive consequences of unchecked ambition and the powerful influence of superstition in shaping Macbeth's actions and fate.