In Shakespeare's Macbeth, the main character (Macbeth) receives a prediction about his future in Act I, Scene 3. Describe this prediction.

In Act 1, Scene 3, the three witches (also known as the Weird Sisters) prophesy that Macbeth will first become the Thane of Cawdor, and then will be crowned King of Scotland. They then claim that, though Banquo himself won't be king, he will be father to a line of kings and, in some sense, will be greater than Macbeth. 

This prediction is important for two reasons. First, it plants the seed in Macbeth's brain that ultimately leads him to murder his way to the throne of Scotland. Second, it alludes to Macbeth's tragic downfall. For example, we learn that, though Macbeth will become king, his reign is doomed to failure, as it is Banquo's line, not Macbeth's, that will last as royalty. As such, through this prediction Shakespeare quickly signals that Macbeth will become king, but that his inevitable failure also looms ominously on the horizon.