Calhoun's feeling of encouragement vanished. He winced a little. The isolation syndrome was fully developed. It was a matter of faith that strangers were dangerous. All men were assumed to carry contagion. Once, they'd have been believed to carry bad luck. But a regained primitiveness would still retain some trace of the culture from which it had fallen. If there were three settlements as the pastureslands seen from space suggested, they would not believe in magic, but they would believe in contagion. They might have, or once have had, good reason. Anyhow they would fanatically refrain from contact with any but their own fellow-citizens. Yet there would always be troubles to excite their terrors. In groups of more than a very few there would always be an impulse against the isolation which seemed the only possible safety in a hostile world. The effectiveness of the counter-instinct would depend in part on communications, but the urge to exogamy can produce ghastly results in a small culture gone fanatic. "I think," said Calhoun, "that I'd better come with you. But the people here have to know I've gone. I wouldn't like them to heave my ship out to space in pure panic because I didn't answer from inside it!" "Leave a writing," said Hunt's deep voice, as impatiently as before. "I'll write it. Make them boil, but they don't dare follow us!" "No?" "Think One City men," asked the stocky man scornfully, "will risk us toppling avalanches on them?" Calhoun saw. Amid mountain-country in a polar zone, travel would be difficult at best. These intruders had risked much to come here for him. But they were proud of their daring. They did not believe that the folk of lesser cities--tribes--groups than theirs had courage like theirs. Calhoun recognized it as a part of that complex of symptoms which can begin with an epidemic and end with group-madness. "I'll want this--and this--and that," said Calhoun. He wouldn't risk his microscope. Antibiotics might be useful. Antiseptics, definitely. His med-kit--"That's all." "Your blankets," said Hunt. "Y'want them, too." Calhoun shrugged. He clothed himself for the cold outside. He had a blaster in his pocket, but he casually and openly took down a blast-rifle. His captors offered no objection. He shrugged again and replaced it. Starting to take it was only a test. He made a guess that this stocky leader, Hunt, might have kept his community just a little more nearly sane than the group that had set him to the cure of a sick cow. He hoped so. "Murgatroyd," he said to the _tormal_ still clinging up near the control-room's top, "we have a professional call to make. You'd better come along. In fact, you must."