Eddie McDermott paused at the door, then caught his breath and tiptoed into the classroom and to his seat. Mort Eddison, his best friend, looked at him reprovingly; the class had been in session for almost fifteen minutes, and one just didn't come late to Professor Carner's lecture. Especially on the first day. Eddie breathed easier as he saw that Professor Carner's back was to the class as he completed a diagram on the blackboard. "Now then," Carner said. "Suppose you were writing about the—ah—