Years ago in Cambridge, Massachusetts, I met a fellow I knew from a party at our common friend’s home. We met in a bus going down Massachusetts Avenue. Like my friend, whom I knew from MIT, he was Turkish. I asked him what he was doing. He told me he was a doctoral student in mathematics, but I do not remember at which university. Perhaps he was at MIT, too. When I told him a bit about my work in matrix algebra, he nodded with understanding. Then I asked him about his work, and he tried to give me a feeling about it. “Imagine a plane with two lines, one of which is stationary, and the other of which is sliding across it sideways at a uniform speed,” he said, demonstrating the movement with his hands. “Now,” he continued slowly, “if the two lines are perpendicular to each other, the point of intersection will be stationary, but if they are at an angle, the point will be moving, and its speed will depend on the angle between the two lines.” He looked at me to check whether I was following him. “Well,” he resumed his story, “if the two lines are almost parallel, the point of intersection will move at an almost infinite speed as one line slides over the other, but if they are actually parallel, the point will be moving at an infinite speed.” Then he noticed that his stop was coming up, we waved at each other hurriedly, and he scrambled off the bus. This was the last time we met.