As a teenager, I was deeply preoccupied with my fingernails. I could almost always be found scratching chalk with them in my pocket. In Talmud classes at the yeshiva, I once heard: “Rabbi Yohanan said: A mouse in the house is a bad sign for the house.” I began carving the chalk into mouse-like forms and built them a cage out of metal wires - so they wouldn’t reach my home.