The impact of the supernatural forces in "Macbeth" are the motivations for the actions of the main characters throughout the play. At the beginning of the play, Macbeth and Banquo encounter the three witches who predict three things.
1. Macbeth, who is currently Thane of Glamis will be Thane of Cawdor.
2. Macbeth will also be king of Scotland
3. Banquo will not be king himself, but will be the father of kings.
When Macbeth returns to Duncan, he is quickly named Thane of Cawdor. Then he and his wife plot to make second prophecy come true by killing Duncan, the king. Then, he kills Banquo to prevent him from being "the father of kings". The play continues to show the sad consequences of Macbeth's actions.
Then, In order to secure a wicked ending for Macbeth, the witches return and again predict three things.
1. Macbeth should be wary of Macduff.
2. Macbeth will not be killed by " no one given birth to by a woman".((V,i,90)
3. Nothing will happen to Macbeth unless " Great Birnam Wood to high Dunsinane Hill/ Shall come against him. ( V,i, 104-105)
This supernatural prediction gives Macbeth the mistaken belief that he has nothing to fear, except from Macduff, whose family Macbeth kills. Then Macduff flees to England and Macbeth believes he is safe. However, as is often the case with witches in Elizabethan times, their words have double meaning.In the end, Macbeth's false sense of security because of the witches supernatural predictions eventually lead to his downfall
The presence and the role of the supernatural elements which forcefully impact the play in the followiing three incidents:
1. The ambiguous prophecies of the evil witches in ActI sc.3 and ActIV sc1 which deliberately mislead Macbeth and his wife to murder the King to satisfy their over ambitious lust for power:
"All hail, Macbeth, thou shalt be king hereafter!"
"Be bloody, bold, and resolute; laugh to scorn
The power of man, for none of woman born
Shall harm Macbeth."
2. The supernatural apparition of the dagger in ActII sc.1 which serves as a catalyst to make Macbeth decide quickly and certainly to murder Duncan:
"Art thou not, fatal vision, sensible
To feeling as to sight? or art thou but
A dagger of the mind, a false creation,
Proceeding from the heat-oppressed brain?"
3. Banquo's Ghost which occupies Macbeth's seat at the banquet table in Act III sc.4 and prompts Macbeth to remark in the presence of all the other nobles of Scotland:
"Thou canst not say I did it: never shake
Thy gory locks at me."
After this incident the other nobles begin to suspect that Macbeth has murdered Banquo.