We become acquainted with the three witches from the very beginning of the play whom were responsible for the introducing ideas to Macbeth that lead to Duncan's death and Macbeth's destruction but not for Macbeth's actions themselves. Temptations await all, but how those temptations are handled depends on one’s character and moral resolve.
Macbeth’s witches serve to advance the story, reveal human weakness, heighten the tension while giving hint of things to come, but they do not control Macbeth. Power over Macbeth existed in their limited ability to support an idea resides already in his head. Their role became clear when Hecate speaks to them, “And which is worse, all you have done Hath been but for a wayward son.” (Act III Scene 5) She suggests that they do not have the power to make him do the evil and the mischief that they want. Nor do they need that power. Macbeth proves fully capable of doing all the mischief and evil on his own though one can wonder if Macbeth ever has a chance of doing what he morally should do after he hears the witches' prophecies which may have been the intent all along. However, more realistic to believe that Macbeth took responsibility for his own actions and in the end; he alone makes the final decisions to his death. None can predict the future, not even the witches, they can add temptation, and influence Macbeth mentally, but they cannot control his destiny. He creates his own misery when controlled by the guilt of his actions. This causes him to become insecure which leads him to commit more murders. Great enticements arise from the witches, but in the end, Macbeth makes the decision to fall for the temptation or to stand strong and resist their appeal.
When the witches hold out their promises to Macbeth the only surety they have comes from the knowledge of his ambition so that he only needs the suggestions of things that the future could hold to goad him on. In the end this reflects all they need assurance of. There is no sense of moral right to keep him from murder and only hesitates because he fears the earthly consequences not because sinful. “… If the assassination could trummel up the consequences.” “…But in these cases we still have judgment here.” (Act I Scene 7) He does not realize that his struggle is not against evil but for maintaining his goodness.
They want to manipulate, but they do not need to control Macbeth. With the character flaws that Macbeth possesses, it grants enough assurance that allows their prophecy to take hold. Interestingly the witches do not ask for anything in return for their prophecies. Throughout history in both written works and spoken lore, you are given something and something must be taken. Everything has a price and paid in full regardless. Not so with Macbeth as his soul is already in trouble before he meets the witches. This in itself may have been payment enough for the witches as he seems the logical choice to fulfill their needs.
In the first set of predictions the witches announce what the future holds: "Hail to thee, Thane of Cawdor! All hail, Macbeth, that shall be king hereafter!" (Act I Scene 3). With the first part of the predictions, Macbeth's future as dictated by the witches holds true because he becomes Thane of Cawdor by the king and could do nothing to stop it. With the second part, not trapped by the situation, he thus has some control to decide whether to become King or not. In Act I Scene 2 and 3, Macbeth does not think of becoming king. However, the witches prophesies make Macbeth doubt his principles and sets out to become king. Later in the play, we see how Macbeth's mind changes from good nature to evil through Lady Macbeth’s influence. In her speech: "come, you spirits that tend on mortal thoughts, unsex me here" (Act I Scene 5) led us to believe that she calls upon the evil spirits of the witches to help her fulfill the horrendous deed of killing Duncan, King of Scotland, and aids in the