In William Shakespeare's play, Macbeth, the Weird Sisters (or three witches) make three predictions for Macbeth.
First the women address him by the title of "Thane of Glamis." (A "thane" is like a Scottish earl.) Of course, Macbeth already has this title, but it is still interesting to note that they know who he is.
The next prediction the women make is to call him by a new name:
All hail, Macbeth! Hail to thee, Thane of Cawdor!
This is something Macbeth does not understand because the Thane of Cawdor is alive, and Macbeth knows nothing about the circumstances surrounding the traitor's capture.
Their last prediction is:
All hail, Macbeth, that shalt be king hereafter!
The witches have just told Macbeth that he will one day be King.
Macbeth is distracted by their words, contemplating what this could mean to him. (Banquo notices his preoccupation and points it out to him.)
When Macbeth then receives the title and lands of the former Thane of Cawdor as a reward for his valiant service to the King during battle, he begins to believe that the witches' words must be true. And with this is mind, he anticipates he will be King.
Whereas Banquo is cautious about the witches' predictions, seeing them as servants to the "powers of darkness," Macbeth does not hesitate to embrace what they have promised him (as he sees it), and he begins planning what must be done.