The breeze that came in from the red deserts was soft and peaceful, with no trace of danger in it, no howl of a devil dog from the desert's brim, no chirrrr of a winged horde of locusts coming to devour the crops. Where, then, was the source of his feeling of danger? Had Malovar begun to doubt him? Was the Martian ruler considering what action he might take at the next time of the testing? At the thought, a slight shudder passed over the tall trader as if the desert wind had suddenly become tinged with a trace of bitter chill. No, that could hardly be the source of the trouble he sensed. He was no telepath, he could not read Martian minds, nor they his. What then was the source of the trouble that he sensed? * * * * * From inside the store a soft voice called out, "_Send motan_." Larkin went inside. The Martian had entered by the side door. He was tall and slender, with a big chest and a skin the color of old copper. His features were finely moulded, the face of a dreaming esthetic. In one hand he held a jewel, one of the Martian opals, uncut. At a glance Larkin knew that this opal was worth approximately seventy dollars delivered on Earth. In the other hand the Martian held a list which he was turning in nervous, uncertain fingers. "Yes, Seekin?" Larkin said. The Martian smiled. A little uncertainly he pushed the list across the counter. "I do not need all of these for me and mine, but the ground is prepared and ready, and if I have these minerals I will be able to grow more than I need. Then there will be something over for someone else to use in the time of scarcity." His voice was as soft as a breeze, there was no hint of a demand in it. But there was a pleading in the eyes that looked at the human. Larkin took the list. Rapidly translating the Martian script, he saw that Seekin wanted approximately five grams of powdered cobalt, copper, boron, manganese, with traces of iron, zinc, and calcium. Phosphorus also was included and a smattering of trace elements. The trader went quickly to the bins and filled the order, tossing the correct amount of the powdered elements into the agitator for mixing. He spun the crank of the agitator and the machine hummed softly. The powdered minerals poured from the spout. He bagged the mixture. His practiced eye told him that the cost of these minerals, delivered here on Mars, was approximately two hundred dollars. The Martian's eyes became fixed longingly on the little bag when Larkin laid it on the counter. There was an eagerness in the eyes that was almost as strong as the eagerness for life itself. But there was uncertainty too. He fumbled with the opal. "This is all we have," he said. Larkin grinned. "It's odd, isn't it, how things achieve a balance? Those minerals come to just exactly the price of this jewel." A glow lit the Martian's face. "Do you mean it?" "Of course." "But--" "Take the minerals, give me the opal. It is a fair trade."