For example, in the play, the Weird Sisters prophecy that Macbeth will become King of Scotland. However, they do not make this happen directly. Instead, they plant the idea in Macbeth's mind and use their spells to fuel his ambition and desire for power. Macbeth's own actions, driven by his ambition and the prophecies of the Weird Sisters, ultimately lead to his downfall.
Therefore, while the Weird Sisters have the power to foresee the future and influence events, they cannot directly make anything happen. Their role in the play is to set in motion a chain of events that leads to Macbeth's tragic fate.