Bill knew very well just what capabilities for effort the human body holds. It has certain definite limits. After a few hours of such labor as this the body is tired,--tired clear through and aching in its muscles. Despondency takes the place of hope, the step is somewhat faltering, hunger assails and is forgotten, even the solace of tobacco is denied because the hand is too tired to grope for and fill the pipe. Thereafter comes a deeper stage of fatigue, one in which every separate step requires a distinct and tragic effort of will. The perceptions are blunted, the uncertainty of footfall is more pronounced, the stark reality of the winter woods partakes of a dreamlike quality. Then comes utter and complete exhaustion. In its first stages there can still be a few dragging or staggering steps, a last effort of a brave and commanding will. Perhaps there is even a distance of creeping. But then the march is done! There is no comeback, no rallying. The absolute limit has been reached. But fortunately, lying still in the snow, the wanderer no longer cares. He wonders why he did not yield to this tranquil comfort long since. Bill began to realize that he was approaching his own limit. The weary miles crept by, but with a tragic languor that was like a nightmare. But time flew; only a little space of daylight remained. Bill's leg muscles were aching and burning now, and he had to force himself on by sheer power of his will. He would count twenty-five painful steps, then halt. The wind had taken a more westerly course by now, and the snow was no longer melting. The air was more crisp: probably one night would serve to recrust the snow. But the fact became ever more evident that the darkness would overtake him before he could reach the cabin. But now, curiously, he dreaded the thought of pausing and making a fire. Partly he feared--with the age-old fear that lay buried deep in every cell--the long, bitter night without shelter, food or blankets; but even the labor of fire-building appalled his spirit. I would be a mighty task, fatigued as he was: first to clear away the snow, cut down trees, hew them into lengths and split them--all with a light camp ax that only dealt a sparrow blow--then to kneel and stoop and nurse the fire. His woodsman's senses predicted a bitter night, in spite of the warmth of the day. It would harden the snow again, but it would also wage war against his life. All night long he would have to fight off sleep so that he could mend the fire and cut fuel. It mustn't be a feeble, flickering fire. The cold could get in then. All night long the flame must not be allowed to flag. In his fatigue it would be so easy to dose off,--just for a moment, and the fire would burn out. In that case the fire of his spirit would burn out too,--just as certain, just as soon. Late afternoon: already the shadows lay strange and heavy in the distant tree aisles. And all at once he paused, thrilled, in his tracks.