By the time his mother began leaving the cave on hunting expeditions, the cub had learned well the law that forbade his approaching the entrance. Not only had this law been forcibly and many times impressed on him by his mother’s nose and paw, but in him the instinct of fear was developing. Never, in his brief cave-life, had he encountered anything of which to be afraid. Yet fear was in him. It had come down to him from a remote ancestry through a thousand thousand lives. It was a heritage he had received directly from One Eye and the she-wolf; but to them, in turn, it had been passed down through all the generations of wolves that had gone before. Fear!—that legacy of the Wild which no animal may escape nor exchange for pottage. So the grey cub knew fear, though he knew not the stuff of which fear was made. Possibly he accepted it as one of the restrictions of life. For he had already learned that there were such restrictions. Hunger he had known; and when he could not appease his hunger he had felt restriction. The hard obstruction of the cave-wall, the sharp nudge of his mother’s nose, the smashing stroke of her paw, the hunger unappeased of several famines, had borne in upon him that all was not freedom in the world, that to life there was limitations and restraints. These limitations and restraints were laws. To be obedient to them was to escape hurt and make for happiness. He did not reason the question out in this man fashion. He merely classified the things that hurt and the things that did not hurt. And after such classification he avoided the things that hurt, the restrictions and restraints, in order to enjoy the satisfactions and the remunerations of life. Thus it was that in obedience to the law laid down by his mother, and in obedience to the law of that unknown and nameless thing, fear, he kept away from the mouth of the cave. It remained to him a white wall of light. When his mother was absent, he slept most of the time, while during the intervals that he was awake he kept very quiet, suppressing the whimpering cries that tickled in his throat and strove for noise. Once, lying awake, he heard a strange sound in the white wall. He did not know that it was a wolverine, standing outside, all a-trembling with its own daring, and cautiously scenting out the contents of the cave. The cub knew only that the sniff was strange, a something unclassified, therefore unknown and terrible—for the unknown was one of the chief elements that went into the making of fear.