Double, double toil and trouble / Fire burn, and cauldron bubble.
— The Witches, William Shakespeare’s Macbeth
———
The boil, the fourth essential step in brewing beer, is the main event on brew day. This is where newborn wort reaches its full potential and becomes fully developed yeast food. If you brew indoors on your kitchen stove, your house fills with the heady aromas of malt and hops. If you brew outdoors on a propane burner, you find yourself drawn to the brew kettle, as if it’s some kind of mystical cauldron. And, in some ways, it is.