Macbeth's Crisis of Conscience
Ever had that moment when you know you're about to do something terrible but can't stop yourself? That's exactly where Macbeth finds himself in this crucial scene. He's left Duncan's dinner party and is now pacing around his castle, completely torn apart by what he's planning to do.
Macbeth's famous soliloquy starts with "If it were done when 'tis done, then 'twere well it were done quickly" - basically, he's saying if he's going to commit this murder, he needs to get it over with fast. But here's the thing: he's terrified of the consequences that might follow.
What makes this scene brilliant is how Shakespeare shows us Macbeth's moral reasoning. He lists all the reasons why killing Duncan is wrong: Duncan is his king, his guest, and his relative. Plus, Duncan's actually a really good king who doesn't deserve to die. Macbeth knows that if he teaches others that murder is acceptable, someone might eventually turn on him too.
Key Point: Macbeth admits he has no good reason to kill Duncan except his own "vaulting ambition" - and he knows that unchecked ambition usually leads to a person's downfall.