Professor Clarke stopped talking. Jimmy and I said nothing. The only sound was the hum of traffic outside. "And that is the way it is, gentlemen," said Professor Clarke, finally. "_Quando cadet Roma, cadet et mundus._ When Rome falls--the world!" He sipped the beer which by now had gone flat. "Do you believe me?" Jimmy and I exchanged glances. "Have another beer," said Jimmy. "On the house." "I see." Professor Clarke sighed. "Well, I cannot really blame you, gentlemen. I only hope you do not live to regret it." He got up and put a coin on the bar. Jimmy went to make change. Then we became aware of automobile horns blasting steadily on a rising note of urgency. Jimmy and I ran outside. Traffic was piling up rapidly in the street. And as far as we could see in every direction, all the traffic lights had turned green! "Holy cow!" said Jimmy. "He was telling the truth!" "So it appears," said a voice at my elbow. I turned. It was the professor. There was a sad, wistful expression on his face. "_Quod erat demonstrandum_," he said softly. "Q.E.D." Then, as the horns got louder, and we could hear drivers cursing, he strode down the street and around the corner. "Professor!" I yelled. "Wait!" I started to run after him when the horns stopped blowing. Cars started moving again, and many of the traffic lights had turned red. Jimmy wiped his face in obvious relief. "Must have been a short circuit," he said hoarsely. "But for a minute--" "Yes," I said. "A short circuit. Or maybe--a dry run to test facilities for the big day?" Neither one of us said anything, but we both had the same thought as we returned to the bar. I picked up the subway token the professor had left there. I flipped it in the air several times and looked at Jimmy. He nodded in agreement. I went out and headed for the nearest subway. Q.E.D.? Transcriber's Note: This etext was produced from _Analog Science Fact & Fiction_ August 1963. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed. Minor spelling and typographical errors have been corrected without note.