How does Macbeth's overconfidence lead to self destruction?      

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teachersage eNotes educator| Certified Educator

The witches, Hecate in particular, lure Macbeth into overconfidence with their prophecies, which make it seem impossible for him to lose the battle against the invading army. As Hecate says, it is easy to trick mortals. She tells the witches that they

Shall raise such artificial sprites
As by the strength of their illusion
Shall draw him on to his confusion.
The prophecies--that he can't be defeated until Birnam Wood comes to Dunsinane, nor can any man born of woman defeat him--give Macbeth a false sense of security, because they suggest that since it is impossible for either of these two things to happen, it is impossible for him to lose. With these prophecies backing him, Macbeth, though badly outnumbered, decides to fight rather than flee and says:
 I have almost forgot the taste of fears.
He has forgotten too that the witches may not have his best interests at heart and may be leading him astray with tricky double talk. Had he not been so confident that the witches were speaking literally, he might have made a rational assessment of his situation, then retreated and regrouped, rather than being so reckless about the danger he was entering into. 
rrteacher eNotes educator| Certified Educator

Macbeth becomes overconfident after receiving the prophecies from the apparitions conjured by the witches. The first, an armored head, tells him to beware the Thane of Fife, but the next two, a bloody child and a child wearing a crown, tell him that he cannot be killed except by a man "not of woman born," and then only when "Great Birnam Wood to high Dunsinane Hill sahll come against him." He responds confidently:

Rebellion's head, rise never, till the Wood 
Of Birnam rise, and our high-placed Macbeth(110) 
Shall live the lease of nature, pay his breath 
To time and mortal custom.

Despite these assurances, Macbeth still feels it necessary to kill Macduff, (the Thane of Fife) but because he is not at his castle, he survives, but his family does not. It is difficult to say that his overconfidence caused his death, though. Rather his relentless ambition, which drove him to commit one murder after another, seems to be to blame. His overconfidence made him believe that he would be victorious, but given the extent to which he had alienated the important men of Scotland, it is difficult to see what his overconfidence had to do with it.