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 grabbed her phone and called her roommate Pim, who fed Gerald on weekends. "Did you write a note FROM my sourdough?" she demanded. Long pause. "I thought YOU wrote it," Pim said slowly. "Nadia. I have never touched the thermostat." Behind Nadia, the kitchen tap turned itself on.