"Really no trouble at all," Carr assured him. "You gave me a very exciting afternoon." He added wistfully. "I must confess that you've aroused my curiosity." "Linthicum dotes on anything mathematical, especially when it's like a puzzle," Mrs. Carr told him. "Why, once," she continued, with a kind of roguish indulgence, "he made all sorts of tabulations on _horse races_." "Er ... yes ... but only as a concrete example of the calculus of probabilities," Mr. Carr interposed quickly. But his smile was equally indulgent. Her hand was on his shoulder, and he had reached up his own to cover hers. Frail, yet somehow hearty, withered, yet somehow fresh, they seemed like the perfect aged couple. "I promise you," Norman told Carr, "that if I revolutionize the science of sociology, you'll be the first to hear of it." * * * * * As soon as he was home, Norman got out the code. "_W_" was the identifying letter at the top of the first sheet. He thought he remembered what that meant, but he looked it up just to be sure. "_W_--To conjure out the soul." Yes, that was it. He turned to the supplementary sheet covered with Carr's calculations, and carefully decoded the final equation. "_C_--Notched strip of copper." He nodded. "_T_--Twirl sunwise." He frowned. He would have expected them to cancel out. Good thing he'd gotten a mathematician's help in simplifying the seventeen equations, each representing a different people's formula for conjuring out the soul--Arabian, Zulu, Polynesian, American Negro, American Indian, and so on; the most recent formulas available, and ones that had known actual use. "_A_--Deadly amanita." Bother! He'd been certain that one would cancel out. It would be a bit of time and trouble getting a deathcup mushroom. And there was another even more difficult item. Well, he could manage without that formula, if he had to. He took up two other sheets--"_V_--To control the soul of another," "_Z_--To cause the dwellers in a house to sleep"--and set to work on one of them. In a few minutes he had assured himself that the ingredients presented no special difficulties, save that _Z_ required a Hand of Glory to be used as well as the graveyard dirt to be thrown onto the roof of the house in which sleep was to be enforced. But he ought to have little difficulty in filching a suitable severed hand from the anatomy lab. Now he was getting somewhere. With _Z_ he could place the charm in the Gunnison house tomorrow night, and with _V_ activate it. Conscious of a sudden reaction of weariness, he pushed back his chair. For the first time since he had come into the house, he looked at her. She sat in the rocking chair, face turned toward the drawn curtains. When she had started rocking, he did not know. But the muscles of her body automatically continued the rhythmical movement, once it had begun.