What was Big Willy Shakes going for?
The witches are chanting here. Full on, belting it out. And Big Willy's making it obvious for his audience, too. See, usually Shakespeare writes in iambic pentameter, but he switches it up here. The witches' lines are written in something called trochaic tetrameter. That's a mouthful, but it's actually pretty simple once you wrap your brain around it. Let's take a closer look.
A trochee is the opposite of an iamb. It's an accented syllable followed by an unaccented syllable. It sounds like DUM-da. For those of you out there who know your Latin roots, you might know that "tetra" means "four." So "trochaic tetrameter" is a kind of rhythmic pattern that consist of four trochees per line. It sounds like this:
DUMda DUMda DUMda DUMda
Let's see how that works in what the witches say:
double, double, toil and trouble.
fire burn and cauldron bubble.
Usually when Shakespeare ditches his normal meter, something big is happening. He might do it to show someone has gone mad. Or to have super important news delivered.
So what's going on here? It seems Shakespeare is changing his style to separate the witches from the rest of the pack. The nobles speak in iambic pentameter. The commoners speak in prose (or lines with no meter.) And the witches speak in trochaic tetrameter, with rhymes to boot.
In fact, they chant in a singsong way that sounds a lot like a scary nursery rhyme. The meter and the rhyme kind of make the chanting seem a little silly, especially for modern audiences, who don't necessarily believe in witchcraft.
These lines are really supposed to sound as obscure and chant-y as they do when you read them aloud. The witches are saying that twice (double) the amount of trouble will now be brought on Macbeth. In other words, he'd better watch out.
He's in big trouble for killing everyone on his way to the crown. The witches know it will not end well for him and their creepy chant let's us in on it, too.