Perhaps the most frequently told anecdote about Professor Coolidge occurred one day during his analytic geometry class, while discussing the conic sections. Coolidge had the habit of twirling his gold watch and chain, back and forth about his index finger as he lectured. At the start of a particularly vigorous swing, the chain broke, and the valuable watch looped across the classroom and landed, shattered on a stone window sill. Unperturbed Professor Coolidge immediately seized the lesson involved and uttered, “Gentlemen, you have just observed a perfect parabola.”