“You didn’t think of it. It just never occurred to you.” Dazed, Boyd turned to Wayne. “As long as you said it yourself, I agree—idiot savant.”

“No.” Karen spoke very quietly. “No, not in any ordinary sense. Such a person is feeble-minded in all but one respect, where he is brilliant. I used to teach school and know a little psychology. Yesterday I gave Al some special tests I’d worked out. Science, mechanical skill, comprehension—in too many respects he’s a genius,”

“I give up. What is he, then?”

“A mutant,” said Karen.

“And…this weapon—?”

“Alaric tried to tell me, but we couldn’t understand each other,” said Wayne. “And the thing itself burned out very quickly in use. It’s just fused junk now. From what I could gather, though, and by deduction on that basis, I think it projected an intense beam of an inconceivably complex wave form to which one or more important organic compounds in the body resonate. They disintegrated, releasing their binding forces. Or perhaps it was body colloids that were destroyed, releasing terrific surface energies, I’m just as glad I don’t know. There are too many weapons in the world.”

“Mm-m-m—officially I can’t agree with you, but privately I do. Anyway, the inventor is still here—the genius.”

“It takes more than genius,” said Wayne. “It just isn’t possible for any human being to sit down and figure such a thing out in detail. All the facts are available, in handbooks and texts and papers—quantum mechanics, circuit characteristics, physical constants. But even if he knew exactly what he was after, the greatest genius in the world would have to spend months or years in analytical thought, then more time in putting all those facts together into the pattern he was after. And even then he wouldn’t know it all. There’d be a near infinitude of small factors interacting on each other, that he couldn’t allow for. He’d have to build a model and experiment with it, the empirical process known to engineers as getting the bugs out.

“In his incoherent way, Alaric told me his only difficulty was to figure out what to do to meet the danger. All he could think of was to make some kind of weapon. But he hardly spent a second working out the details of that devil’s engine, and his first model was as nearly perfect as his inadequate tools and materials permitted. He knew how to make it.”

With a shuddering effort, Boyd relaxed. He couldn’t look at that small, big-headed figure in the armchair. The ancient human dread of the unknown was too strong in him. He asked slowly:

“What’s the answer, then?”

“Karen and I think we’ve figured it out, and what little Al can tell us seems to confirm our idea. But I’ll have to explain it in a roundabout way. Tell me, how does a person think?”

“Think? Why…well…by logic. He follows a logical track—”

“Exactly! A track. He thinks in chains of logic, if under that we include everything from math to emotional experience. Premise to conclusion. One thing leads to another, one at a time.