And so Old Mok and Ab worked well that winter and the youth acquired such wisdom that his casual advice to Oak when the two were out together was something worth listening to because of its confidence and ponderosity. Concerning flint scraper, drill, spearhead, ax or bone or wooden haft, there was, his talk would indicate, practically nothing for the boy to learn. That was his own opinion, though, as he grew older, he learned to modify it greatly. With his adviser he had made good weapons and some improvements; yet all this was nothing. It was destined that an accidental discovery should be his, the effect of which would be to change the cave man's rank among living things. But the youth, just now, was greatly content with himself. He was older and more modest when he made his great discovery. It was when the fire blazed out at night, when all had fed, when the tired people lay about resting, but not ready yet for sleep, and the story of the day's events was given, that Old Mok's ordinarily still tongue would sometimes loosen and he would tell of what happened when he was a boy, or of the strange tales which had been told him of the time long past, the times when the Shell and Cave people were one, times when there were monstrous things abroad and life was hard to keep. To all these legends the hearers listened wonderingly, and upon them afterward Ab and Oak would sometimes speculate together and question as to their truth. CHAPTER XII. OLD MOK'S TALES. It was worth while listening to Old Mok when he forgot himself and talked and became earnestly reminiscent in telling of what he had seen or had heard when he was young. One day there had been trouble in the cave, for Bark, left in charge, had neglected the fire and it had "gone out," and upon the return of his parents there had been blows and harsh language, and then much pivotal grinding together of dry sticks before a new flame was gained, and it was only after the odor of cooked flesh filled the place and strong jaws were busy that the anger of One-Ear had abated and the group became a comfortable one. Ab had come in hungry and the value of fire, after what had happened, was brought to his mind forcibly. He laid himself down upon the cave's floor near Old Mok, who was fashioning a shaft of some sort, and, as he lay, poked his toes at Beechleaf, who chuckled and gurgled as she rolled about, never for a moment relinquishing a portion of the slender shin bone of a deer, upon the flesh of which the family had fed. It was a short piece but full of marrow, and the child sucked and mumbled away at it in utmost bliss. Ab thought, somehow, of how poor would have been the eating with the meat uncooked, and looked at his hands, still reddened--for it was he who had twisted the stick which made the fire again. "Fire is good!" he said to Mok. The old man kept his flint scraper going for a moment or two before he answered; then he grunted: