This adds to their mystique.
Shakespeare never intends to fully disclose everything there is to know about these women. Instead, he leaves them with us to make up our own minds as we watch Macbeth descend. We know they are responsible for part of Macbeths tragedy. He becomes more dependent on them, illustrating how they slowly replace his moral center. It is also important to realize they are completely aware of what they are doing. They set out to destroy him and he falls into their trap instantly. Their ability to affect Macbeth is compelling and Shakespeare deliberately establishes them as supernatural and powerful creatures to reinforce the humanity of Macbeth. To enhance this affect, the witches apparitions drive Macbeth close to and eventually off the mental edge. After killing Lady Macduff, Macbeth moves beyond any reason. They are source of struggle for him. While their prodding seems to upset him, he asks for it. They keep him in a state of confusion that works to their advantage. In their mystery, symbolize the darkness and chaos that will soon become Macbeths life. Their intent is clear from the beginning of the play. Their declaration of all things being “foul is fair and fair id foul” (I.e.) sets the mood for the play. They are all about confusion. We know not for whom these sisters work, except for the chaos that rules the world. They mean nothing but trouble for Macbeth. They are not from this world so they cannot be held within its realm. Similarly, they are in this world so they are not completey otherworldly. They resemble the Fates in that they seem to have control in Macbeths life and future but Shakespeare never clearly divulges their meaning.
Macbeth is one of Shakespeares masterpieces because it shows us how man can fall so quickly. Macbeth is like every other man in that he possesses a healthy ambition.
The notion of being king sounds good to him and he may very well have been a good king. However, he falls with the slightest temptation. The first and most unusual of temptations are the witches, who encounter Macbeth, tease hi with the notion of being king and proceed to tear him down from the inside out. The witches cannot be blamed completely for Macbeths fall but they illustrate how easy it is to get into the mind of man and persuade him to do something. Desire is a dangerous thing and Macbeth has too many outside forces pressing him to bend against his good nature and sink into evil. The temptation is too great and if it can happen to this man, it can happen to any of us, plain and simple. Macbeth enjoyed a loving marriage with his wife and he had a bright future. He could be like almost every other successful businessman in our modern times. The witches are intended to be a mysterious and nebulous force in Macbeths world to demonstrate that once the seed is planted, it is difficult to remove. While we may see Shakespeares work as old, we should remember that the reason it is still around is because there are elements of truth to his characters. Macbeth was not special and he was not unique; he was normal and that is the most frightening thing about the man we can know. The witches might seem to be more of a spectacle than anything but they represent the weakness of man. They demonstrate that man does not even a good reason to become obsessed about greatness and success — all he needs is a gentle nudge in the right direction.
Shakespeare, William. Macbeth. New York: Washington Square Press. 1959..