On the morning of the third day, his aunt Emily arrived to take charge of things, and he was able to slip away. He drove immediately to Mark Smythe's address. It was one of the better class rooming houses near the campus. The land-lady wasn't going to let him in nor announce him until he explained he was the son of the professor who had vanished. She immediately swung to the other extreme and didn't bother to find out if Mark wanted to see him. "My father was your teacher," Fred said. "Oh? Come on in." There were tennis rackets. On the bookshelves there were tennis books. On a table there was a tennis trophy. Otherwise there was just a bed, a rug, and two or three chairs. "I don't know what I can tell you more than I've already told the police and the reporters," Mark said apologetically. "I guess it's tough, losing your father...." "Yeah," Fred agreed. "I wanted to ask you something though. Dad gave a lecture on his new theory a few days ago, didn't he?" Mark looked at him blankly. Then, "Oh! I guess he did. As a matter of fact I didn't pay much attention to it." He grinned. Then he remembered he should be solemn and stopped grinning. "I--I sort of slipped by it. He made the mistake of telling us ahead of time it was off the course and no questions on it would be in the finals, so I more or less rested up during the period for a tennis match afterwards. Why?" "Didn't you get any of what he said?" Fred persisted. "Oh, a little," Mark admitted. "It was about some system of arriving at the basic laws of nature by pure logic, only what you arrived at didn't agree with facts. Some kind of intellectual curiosity." He thought a minute. "Oh," he said, "I see what you want. Didn't he leave any notes on it? It would be too bad if his theory was lost to the world now that--" He left the rest unsaid. "Maybe you can remember something," Fred coaxed. "Anything. Did he talk about his theory again?" "Next day he gave a lecture on the necessity of unbelief in modern science. It was pretty good. He overemphasized it, though. Some of the kids thought he was making a religion of unbelief." "What did they say about his theory?" Fred asked quickly. "Oh, they were quite impressed. Two of them live--lived here in the rooming house. They were up here that evening tossing it back and forth. I was too tired from the tag match. I let them talk." "What did they think about it?" Mark frowned in an effort to recall. "It had to do with this universe being basically illogical, or at least seeming to be, because it didn't agree with your father's theory. They started building up fantasies on it. One I remember was a good one." "What was that?"