They leave Macbeth to interpret the greetings himself. They plant the seed of ambition into his mind when they predicted all glorious titles to him. They are very influential and can predict future, due to which Macbeth bases all of his decisions on what the witches have told him. When Macbeth has his second meeting with the witches, the scene where Macbeth goes to seek the help of the witches, and as they know he is coming they prepare a potion for him to drink.
The witches know what the outcome of what they said would be ecause apparently witches were not only able to predict the future but also the outcome of each decision that the characters in the play would take and how these characters would change, from noble to evil. This again shows how their role in the play is very important. When Macbeth reaches the cave the witches say, “ By the pricking of my thumbs, something wicked this way comes,” (act 4 scene 1 lines 47-48 ) This clearly shows that the witches have noticed the change in Macbeth as they refer to him as being evil.
The witches lead him to think about murder, being the King and power. Their plan works and soon after in a conversation with Banquo, we see, that murder is going through Macbeth’s mind, in soliloquy, when he mutters to himself, when Macbeth says, “ My thought, whose murder yet is but fantastical” (act 1 scene 3 line 151 ) Not only do the witches spur on his want to be king but they even try to entice Banquo by telling him, “Thou shalt get kings, though thou be none”, (act 1 scene 3 line 71) meaning his heirs will be kings.
Later on in the play Macbeth, when he is king, sets his mind back to this moment and makes him think that Banquo is a threat as his heirs will be Macbeth’s successor. This idea, along with the fact that Banquo knew about the witches and Macbeth’s thoughts on murder, leads to Macbeth wanting Banquo dead. Even though the witches’ greetings affect Macbeth and lead to the murder of Duncan and Banquo, they do not actually directly tell Macbeth to commit these actions.
However if the witches had not greeted Macbeth, he would not have ultimately killed Duncan. The apparitions are very much like the witches greetings. When Macbeth’s questions are un-answered, it tell us that the witches have set the apparitions up to tell Macbeth the information which will affect later decisions, which in fact lead to his death. Macduff would not have hated Macbeth so much if Macbeth would not have killed Macduff’s family. The apparition tells, Macbeth! Macbeth! Macbeth!
Beware Macduff; (Act4 Scene1 line 83) and after the news of Macduff’s flight to England, Macbeth gives orders for Macduff’s family to be killed. So the witches play an imperative part in the outcome once again. The witches also convinced him to continue to walk along the bloody path by advising him to be ‘bloody, bold, and resolute’ and to have ‘no fear’. These predictions gave Macbeth confidence to murder more victims. They also encouraged Macbeth and enabled his conscience to murder as to fulfill the witches’ prophecies.