Theorists cant help it: When asked to explain something, they reach for a piece of chalk. The language of math and physics seems to require a writing implement and a large vertical surface. For two centuries, scientists have turned to blackboards to grapple their thoughts into coherent equations and to intellectually commune with like-minded people. You cant describe supersymmetry by waving your hands. You cant quickly draw a magnet layout for a student using a graphics program. While the world at large is converting to whiteboards, the iconic blackboard still holds a fond and prominent spot wherever theoretical physicists gatherin hallways, auditoriums, and meeting rooms of old buildings and new.