Nadia named her sourdough starter Gerald, the way you name anything you have to feed twice a day and slightly resent. This morning, taped to his jar in flour-dusted handwriting she did not recognize, was a note: WE NEED TO TALK ABOUT THE THERMOSTAT. Gerald had no hands. Gerald had no pen. And yet there it was, the tape still slightly warm.

Nadia decided the bravest thing was to answer. She grabbed a pen, wrote "WHAT ABOUT THE THERMOSTAT?" on a sticky note, and pressed it to the jar. Then she stood back and waited, arms crossed, feeling ridiculous. A bubble rose to the top of Gerald and popped, like a tiny throat clearing.

Nadia decided to test Gerald with a hard question. She wrote: "PROVE YOU'RE SMART." The next morning her electric bill sat open on the counter, every wasteful charge circled in flour, with a note: YOU LEAVE THE OVEN LIGHT ON. SO DOES BARB. Nadia frowned. "Who on earth is Barb?"

Nadia followed Gerald's flour arrow to the apartment next door, where her neighbor's sourdough sat on the windowsill, gray and cold and sad. Gerald wrote one word in shaky flour: BARB. "You have a girlfriend? And she's freezing?" The jar bubbled urgently. This was officially a rescue mission.

Nadia carried Barb's cold jar home and set it on the heated mat right next to Gerald. Within an hour Barb perked up, bubbling brightly. Gerald wrote one happy word: BARB. Then a flour heart. Nadia wiped her eyes. "You softie." Now she had two warm, opinionated jars and a thermostat stuck on 74 forever.