In an after-dinner talk at the fall 2005 meeting of the New England chapter of the AAPT, Professor Robert Arns drew an analogy between classical physics and Classic Coke. To generations of physics teachers and textbook writers, classical physics was the real thing. Modern physics, which in introductory textbooks "appears in one or more extra chapters at the end of the book,...is a "divertimento" that we might get to if time permits." Modern physics is more like vanilla or lime Coke, probably a fad, while "Classic Coke is part of your life; you do not have to think about it twice."