He worked slowly and carefully, keenly aware of his danger. Gradually, as the flame grew stronger, he increased the size of the twigs with which he fed it. He squatted in the snow, pulling the twigs out from their entanglement in the brush and feeding directly to the flame. He knew there must be no failure. When it is seventy-five below zero, a man must not fail in his first attempt to build a fire -- that is, if his feet are wet. If his feet are dry, and he fails, he can run along the trail for half a mile and restore his circulation. But the circulation of wet and freezing feet cannot be restored by running when it is seventy-five below. No matter how fast he runs, the wet feet will freeze the harder.
All this the man knew. The old-timer on Sulphur Creek had told him about it the previous fall, and now he was appreciating the advice. Already all sensation had gone out of his feet. To build the fire he had been forced to remove his mittens, and the fingers had quickly gone numb. His pace of four miles an hour had kept his heart pumping blood to the surface of his body and to all the extremities. But the instant he stopped, the action of the pump eased down. The cold of space smote the unprotected tip of the planet, and he, being on that unprotected tip, received the full force of the blow. The blood of his body recoiled before it. The blood was alive, like the dog, and like the dog it wanted to hide away and cover itself up from the fearful cold. So long as he walked four miles an hour, he pumped that blood, willy-nilly, to the surface; but now it ebbed away and sank down into the recesses of his body. The extremities were the first to feel its absence. His wet feet froze the faster, and his exposed fingers numbed the faster, though they had not yet begun to freeze. Nose and cheeks were already freezing, while the skin of all his body chilled as it lost its blood.
But he was safe. Toes and nose and cheeks would be only touched by the frost, for the fire was beginning to burn with strength. He was feeding it with twigs the size of his finger. In another minute he would be able to feed it with branches the size of his wrist, and then he could remove his wet foot-gear, and, while it dried, he could keep his naked feet warm by the fire, rubbing them at first, of course, with snow. The fire was a success. He was safe. He remembered the advice of the old-timer on Sulphur Creek, and smiled. The old-timer had been very serious in laying down the law that no man must travel alone in the Klondike after fifty below. Well, here he was; he had had the accident; he was alone; and he had saved himself. Those old-timers were rather womanish, some of them, he thought. All a man had to do was to keep his head, and he was all right. Any man who was a man could travel alone. But it was surprising, the rapidity with which his cheeks and nose were freezing. And he had not thought his fingers could go lifeless in so short a time. Lifeless they were, for he could scarcely make them move together to grip a twig, and they seemed remote from his body and from him. When he touched a twig, he had to look and see whether or not he had hold of it. The wires were pretty well down between him and his finger-ends.
All of which counted for little. There was the fire, snapping and crackling and promising life with every dancing flame. He started to untie his moccasins. They were coated with ice; the thick German socks were like sheaths of iron halfway to the knees; and the moccasin strings were like rods of steel all twisted and knotted as by some conflagration. For a moment he tugged with his numb fingers, then, realizing the folly of it, he drew his sheath-knife.
But before he could cut the strings, it happened.
Jack London, from "To Build a Fire"