"By using the verifier." Hume sat crosslegged, his plasta-hand resting on one knee. "Fifty years ago, we would have had to keep rather a lengthy watch to be sure of a free world. Now, we plant verifiers at suitable test points. Intelligence means mental activity of some sort--any of which would be recorded on the verifier." "Amazing!" Starns extended his plump hands to the flames in the immemorial gesture of a human attracted not only to the warmth of the burning wood, but to its promise of security against the forces of the dark. "No matter how few, or how scattered your native thinkers may be, you record them without missing any?" Hume shrugged. "Maybe one or two," he grinned, "might get through such a screening. But we have yet to discover a planet with such a sparse native life as that at the level of intelligence." Yactisi juggled a cup in and out of the firelight. "I agree, this is most interesting." He was a thin man, with scanty drab gray hair and dark skin, perhaps the result of the mingling of several human races. His eyes were slightly sunken, so that it was difficult in this light to read their expression. He was, Hume had already decided, a class one brain and observant to a degree, which could either be a help or a menace. "There have been no cases of failure?" "None reported," Hume returned. All his life he had relied on machines operating, of course, under the competent domination of men trained to use them properly. He understood the process of the verifier, had seen it at work. At the Guild Headquarters there were no records of its failure; he was willing to believe it was infallible. "A race residing in the sea now--could you be sure your machine would discover its presence?" Starns continued to question. Hume laughed. "Not to be found on Jumala, you may be sure of that--the seas here are small and shallow. Such, not to be picked up by the verifier, would have to exist at great depths and never venture on land. So we need not fear any surprises here. The Guild takes no chances." "As it always continues to assure one," Yactisi replied. "The hour grows late. I wish you rewarding dreams." He arose to go to his own bubble tent. "Yes, indeed!" Starns blinked at the fire and then scrambled up in turn. "We hunt along the river, then, tomorrow?" "For water-cat," Hume agreed. Of the three, he believed Chambriss the most impatient. Might as well let him pot his trophy as soon as possible. The ex-pilot deduced there would be little cooperation in exploration from that client until he was satisfied in his own quest. Rovald, Wass' man, lingered by the fire until the three civs were safe in their bubbles. "River range tomorrow?" he asked. "Yes. We can't rush the deal." "Agreed." Rovald spoke with a curtness he did not use when the civs were present. "Only don't delay too long. Remember, our boy's roaming around out there. He might just be picked off by something before these stumble-footed civs catch up with him."