How that audience did boil! And they boiled because every man jack of them, in his heart of hearts, knew that Fradin was right. I knew it the minute he said it. And they knew it too. When he said that "ether" was only a word used by fools to conceal their own ignorance, he had hit the nail exactly on the head. For that is precisely what it is. Nobody has ever seen the ether, felt it, smelled it, heard it, touched it. Scientists of the past century, needing a mechanical device to account for the observed propagation of electro-magnetic radiations such as light and the then little known radio waves, had invented the ether to carry those radiations, invented it out of whole cloth. Fradin's hearers knew he was right. Taken individually, when they were calm, they would have admitted it. But they were in a group and he was calling them fools right out in public. Mass hysteria got them. They boiled over and very promptly demanded that he prove his statements. He refused to do it. Absolutely refused. * * * * * "We demand that you produce your proof," Ramsen howled. "You have called us fools and said you could prove it. We demand that you _do_ prove it." "I--" Fradin began. He wet his lips. His face had whitened. It wasn't a gentle, kindly face any more. It was the face of a badly scared man. Fradin was scared. But he wasn't scared of those engineers who were shouting at him. He was scared of something else. "Speak up," Ramsen roared. "Produce your proof!" "I can show you mathematical proof," Fradin offered. How they howled at that, all except the tall, thin, hawk-nosed individual sitting two seats down from me. He took no part in the demonstration. Instead he got up and very quietly went out of the room. As he walked out, I again got the impression that I ought to know him. But I still couldn't place him. A reporter sees too many people to remember all of them. "Mathematical proof, unless supported by incontrovertible experimental evidence, is not sufficient," Ramsen thundered. "We demand that you produce experimental proof." By experimental proof, he meant an actual instrument of some kind to demonstrate Fradin's claims--some gadget that they could see and feel and examine, something they could take apart and put back together again, something that they could watch in operation. Ramsen was quite right in making such a demand, for without experimental evidence to back it up, mathematical theory is more often than not just so much hot air. "Your demand is just," Fradin faltered. "I fear in the heat of argument I made statements I do not care to support. I do not choose to produce the experimental evidence that I have." He didn't say another word. Instead, he turned and walked off the platform, going out through a door at the back. Nor did he enter the lecture hall where the meeting was being held. He walked out of the room. And he didn't come back.