Mitch realized dismally that he loved technological civilization, its giant tools, its roar of mighty engines, its proud structures of concrete and steel. He could sacrifice his love for particular people, for particular places and governments--but it was going to be harder to relinquish mechanical civilization for some stone-age culture lingering in an out-of-the-way place. Changing tribes was easy, for all tribes belonged to Man, but renouncing machinery for jungle tools would be more difficult. A man could change his politics, his friends, his religion, his country, but Man's tools were a part of his body. Having used a high-powered rifle, the man subsumed the weapon, made it a part of himself. Trading it for a stone axe would be like cutting off his arm. Man was a user of tools, a shaper of environments. _That was it_, he thought. The reason for his sudden rebellion, the narrow dividing line between tolerable and insufferable wars. A war that killed human beings might be tolerable, if it left most of civilizations' industry intact, or at least restorable, for although men might die, Man lived on, still possessing his precious tools, still capable of producing greater ones. But a war that wrecked industry, left it a tangled jumble of radioactive concrete and steel--that kind of war was insufferable, as this one threatened to be. The idea shocked him. Kill a few men, and you scratch the hide of Historical Man. But wreck the industry, drive men out of the cities, leave the factories hissing with beta and gamma radiation, and you amputate the hands of Historical Man the Builder. The machinery of civilization was a living body, with organismic Man as its brain. And the brain had not yet learned to use the body for a constructive purpose. It lacked coordination, and the ability to reason its actions analytically. Was _he_ basing action on analytic reason? Another hour had passed. And then he heard it. The sound of faint sonar communication. Quickly he nosed upward to twenty feet, throttled back to half speed, and raised the periscope. With his face pressed against the eyepiece, he scanned the moonlit ocean in a slow circle. No lights, no silhouettes against the reflections on the waves. He started the pumps and prepared to surface. Then the conning tower was snorting through the water like a rolling porpoise. He shut off the engines, leaving the sub in utter silence except for the soft wash of the sea. He adjusted the sonar pickups, turned the amplifier to maximum, and listened intently. Nothing. Had he imagined it? He jabbed a button, and a motor purred, rolling out the retractable radar antenna. Carefully he scanned the sky and sea, watching the green-mottled screen for blips. Nothing--no ships or aircraft visible. But he was certain: for a moment he had heard the twitter of undersea communicators. * * * * *