"My thought, whose murder yet is but fantastical, shakes so my single state of man that function is smother"d in surmise, and nothing is, but what is not" (1.3.138-141).
The apparitions" second set of prophecies warned Macbeth to beware of Macduff. They also advised him that no one born from a woman would be able to harm him. This gave Macbeth a false sense of confidence that Macduff was not a threat to him, not realizing that Macduff was delivered by cesarean section and not born through normal childbirth. Macduff did eventually kill Macbeth but this was not fate. Had Macbeth not made the choice to kill the King and take the throne, Macduff would not have avenged the King's murder by killing Macbeth. Lastly, the witches tell Macbeth that he will not be conquered until Birnam Wood meets Dunsinane Hill, a seemingly impossible act. Macbeth could never have foreseen that Birnam Wood was actually Malcolm's army camouflaged with tree branches. Birnam Wood did meet Dunsinane Hill and Macbeth was defeated but again this was not fate. If Macbeth did not kill the King and take the throne, Malcolm, King Duncan's son, would never have ordered his army to attack. .
Lady Macbeth's pressure and manipulation impaired Macbeth's judgment and influenced him to act on his evil thoughts. Lady Macbeth sought the power of a queen and was the driving force which instigated the murder of King Duncan. If it were not for Lady Macbeth's influence, Macbeth's ambition would not have been strong enough to cause him to murder the King. This was evident when Lady Macbeth urged Macbeth to kill King Duncan and was even ready to do it herself had the King not reminded her of her father. This was also demonstrated when Macbeth decided against murdering the King. Lady Macbeth belittled him for not being able to commit murder and threatened to take away her love for him if he did not. This threat won Macbeth over and he agreed to murder King Duncan.