The Prince of Cumberland! that is a step
On which I must fall down, or else o’erleap,
For in my way it lies.
– William Shakespeare
Macbeth, Act 1, Scene 4. Macbeth realizes that to achieve his ambition of becoming king, he must kill not only Duncan, but also Malcolm who is next in line to the throne. Not content to leave it to fate, Macbeth decides to act on his own free will and eliminate any obstacle to the Witches’ prophecy that he will be king – including Malcolm.