Here's the full verse:
> **Double, double toil and trouble;
> Fire burn and caldron bubble.
> Fillet of a fenny snake,
> In the caldron boil and bake;
> Eye of newt and toe of frog,
> Wool of bat and tongue of dog,
> Adder's fork and blind-worm's sting,
> Lizard's leg and howlet's wing,
> For a charm of powerful trouble,
> Like a hell-broth boil and bubble.
> Double, double toil and trouble;
> Fire burn and caldron bubble.
> Cool it with a baboon's blood,
> Then the charm is firm and good.**
The phrase "double, double toil and trouble" serves as a sort of incantation, highlighting the witches' intent to double down on their efforts and increase the power of their curse. The rest of the verse describes the grotesque ingredients they are adding to their cauldron, each one representing a different kind of darkness and ill-omen.