logic says must be the only possible way a universe can be constructed and operate. It's beautiful and logically complete, but not applicable. No pragmatic value."

"Congratulations on the book. But, damn it," Horace said, "it attacks my most basic faith. Logic. Reason."

"Faith?" Martin echoed, amused. "Yes, perhaps you're right. That's a word that's foreign to my thinking. Belief is so unnecessary."

"You don't mean that."

"But I do."

Horace pondered. "I can prove otherwise. You believe—as an example—that your wife is faithful to you." It was a statement rather than a question.

"As a matter of fact—I don't. I act upon the greater probability that she is. I don't hire detectives to follow her. Nor do I throw her into situations to test her faithfulness. I admit the possibility that she's unfaithful to me. If evidence came that she was, I might confront her with the evidence. Where does belief become necessary?"

"Do you believe your son will become a success in life?" Horace asked.

"No. I've done everything I could think of to increase the probability that he will. One of the things I've done is to instill in him the realization that belief is unnecessary in thinking. Surely, as a scientist, you realize that nothing we use in science finds its value or validity from human belief. If, tomorrow, evidence were brought forth that trigonometry is based on fallacy I'm sure that mathematicians would use that evidence to revise their entire field."

"But belief is instinctive; as instinctive as thought itself."

"I admit it's a natural way of thinking. It has to be weeded out."

"So you're sure you don't believe in anything," Horace said slyly.

"Such statements are verbal traps," Martin said. "They mean nothing. You want me to imply that I believe I believe nothing, and therefore I have at least one belief. But as a matter of fact I've built up a sort of mental mechanism for discovering beliefs in my thinking and dispelling them by going to the roots and showing myself why I believed. Belief springs up in the mind like weeds in a garden. Constant weeding is the only solution." He glanced at his watch and frowned uneasily. "Eleven o'clock. We'd better break this up and join the women. We'll have to get together again soon. By the way, do you and your wife play Canasta? My wife loves it."

They had been moving toward the door. Now they entered the living room, to find the two women playing the game.

"Time we were going, dear," Martin said. "And sometime soon make plans to have Horace and Ethel over for an evening of four-handed Canasta."

At the front door vows of an early reunion were repeated. But they were never to be fulfilled. On the following Tuesday Horace vanished.

This time there were no actual eye witnesses. The time was somewhere between seven and seven-ten Tuesday morning; the place; Horace Smith's bathroom.

Ethel Smith was in the kitchen preparing breakfast. Horace was in the bathroom. He called out, "Ethel! I've got it!"

"What have you got?"

But even as Ethel called out, she heard the sound of the electric razor falling to the tile floor, and there was no answer from the bathroom. Nothing but silence and, as she described it later, a feeling that she was alone in the house.

At the time, however, she wasn't alarmed. She half expected some muttered profanity over the dropping of the razor. She didn't wait for it exactly. Instead, she picked up the spatula and expertly scooped the eggs onto their two plates and carried them to the breakfast nook. Next she poured the coffee. Then, placing some bread in the toaster, she started back to the stove, calling, "Come and get it, Horace!"

At the stove she started to pick up the aluminum dish containing the bacon. She paused and repeated her call. "Horace!"

It wasn't until then that it occurred to her the falling of the razor might have been an ominous sound. Her mind filled with worried images, she rushed out of the kitchen into the hall leading to the bathroom.

The door was locked.

"Horace!" she called. "Are you all right?" When there was no answer she pounded on the door. "Horace! Speak to me!"

After that she ran outside and around to the bathroom window. It was shut and locked, as she already knew. Not only that, it had been stuck for years.

With an urgency born of a realization that every second might mean the difference between life and death, she ran back into the house and called the fire department. Also the family doctor.

By nine-thirty the police had been called in. By eleven o'clock they had seen the parallel between this disappearance and that of John Henderson.

Martin Grant's first reaction was concern for Ethel. His second reaction was that, twice, he had presented his theory to someone and that person had vanished. His third was accompanied by a twinge of fear. He had just finished presenting his theory to the senior physics class!

This was followed by an amazing realization. He was conceding that there might be a connection between his theory and the disappearances. He laughed it off, but it returned. It disturbed him.

It continued to bother him on Wednesday, so he began to search his mind for reasons. Eventually he found them. There was a distinct analogy between a theory that didn't agree with observable reality, and a pair of disappearances which violated known methods of disappearing.

The analogy was so clear that he began to feel there might be a functional relation between the two. Of course, he concluded, it would be reasonably certain if a large number of the students in the senior group were to vanish also.

This intellectual conclusion became an anxiety neurosis.

So, on Wednesday—after he had scanned the room anxiously to see how many students were absent and discovered to his intense relief that they were all there—he spent the full hour lecturing on the necessity—the vital necessity—of unbelief in all things, especially scientific theories.

But would it work? He vaguely remembered giving Horace a similar lecture.

Wednesday night just before retiring he had another disturbing thought. He had explained the theory to his son. But that had been weeks before, and Fred was steeped in the mechanism of unbelief. Good thing, or he might have been the first to disappear.

"What's the matter with you, Martin? Can't you even answer when—" The rest of what his wife was saying faded in the startled realization that he was eating dinner.

"Sorry, dear," he murmured. "I was thinking." He was trying to recall something that might tell him what day it was. It was obviously evening or they wouldn't be eating dinner. "Uh," he said casually, "what day is today?"

"Saturday," Fred said.

"Now Fred, don't tease your father about his absent-mindedness. This is Thursday."

Thursday! That was right. He had given the lecture on the necessity of unbelief today. There was tomorrow, when he could see if any of the class had disappeared yet. He couldn't be certain, of course. Just because a student didn't show up didn't mean he or she had vanished.

He fixed his eyes on Fred, across the table, and smiled. Fred, at least, was a source of comfort. He knew the theory and hadn't vanished.

"Dad," Fred said. "I've been wondering if you saw a point of similarity in the two disappearances?"

Martin thought, good heavens, does he have any inkling of what I've been thinking? Of course not! He's just fumbling. Better to discourage him. "Sorry, son. There aren't any similarities except accidental ones. I've had the confidence of the police on this. The cases are quite unrelated."

Fred refused to be sidetracked. "Dr. Henderson's face lit up as though a sudden idea had struck him. I talked with some of his students. That's what they all thought. And Horace Smith shouted to his wife, 'Ethel! I've got it!' The next instant in each case they vanished into thin air."

"But that