The 3 Weird Sisters begin in Act 1, Scene 3 by playing on Macbeth's ambition by using foreshadowing, and thus started the tragic pattern. "All hail Macbeth! Hail to thee, Thane of Cawdor! / All hail Macbeth, that shalt be the king hereafter!" (1.3.52-53). This foreshadows how Macbeth will become Thane of Cawdor, and king. The effect of this foreshadowing is to start Macbeth's ambition. It foreshadows how Macbeth is going to become Thane of Cawdor. Immediately afterwards, he does indeed become Thane of Cawdor, but this merely increases his thirst for ambition. At first, Macbeth is content to sit and wait for the events to proceed. "If chance will have me king, why chance may crown me/Without my stir." (1.3.157-159.) However, the Weird Sisters manipulate him, and let his ambition drive him forward into his demise. "I have no spur/To prick the sides of my intent, but only/Vaulting ambition, which o'erleaps itself/And falls on the other."(1.7.25-28). Here is an analogy: the bike is at the top of the hill, full of potential energy. With a little push, the potential energy is converted into kinetic energy. Macbeth is pushed by the Weird sisters, who manipulate him by foreshadowing future events; the push to Thane of Cawdor is enough to get the bicycle moving down the hill; and Macbeth's ambition, formerly dormant, is now converted to energy to drive him forward. The tragic pattern is started.
The Weird Sisters use foreshadowing, equivocation, and ambiguity to give Macbeth a false sense of security, and steer the tragic pattern along. Banquo foreshadows this in 1.3.134-138: "But