Robin and Korree stayed in that cavern for about three days. In that time Korree managed to obtain fairly specific directions from one old-timer as to the cavern they sought. He had also evidently repaired his tribal fences, for Robin could not fail to notice that Korree was always accompanied by a group of anxious and placating Glassies. He imagined that when Korree returned to stay, it would be as a chieftain. The nature of the tribe's culture remained much of a mystery. They were very primitive, yet they seemed to have a complicated series of taboos and ceremonies. There was clearly a very definite code of marriage and family relations, though its limitations were puzzling. Robin discovered something about them, however. One of the circular enclosures was apparently a tribal storehouse, or temple, or arsenal, or magic circle--exactly what he could not tell--save that no family lived within and there were little piles of oddities carefully placed inside its magic circle. The penny Robin had "pulled from the chief's head" reposed therein on a raised mound. The burnt match stick lay beside it. The rest of the contents seemed to be curiously shaped stones, odd bits of animal skin, a skeleton of something big and round which might perhaps have been that of a Moonbowler slain by the hero of the tribe. Several diamond spearheads were there, including some that had fractured in use. And something that glistened like metal. Robin saw this latter, and, stepping boldly inside the magic circle, picked this object up and examined it. It was a knife blade! It was nothing of Terrestrial manufacture. It was about nine inches long and a couple of inches wide at the hilt, tapering down to a point. It was edged on one side, and bore the marks of having been hammered down and shaped by a hand mallet rather than ever having felt the heat of a forge. Engraved in its rather soft white metal were a series of odd hooks and lines that looked like writing of a sort. The hilt end was jagged as if the blade had been snapped off in careless usage. Robin called to Korree and asked him about the object. Korree consulted with the chief and returned. "Sharp thing, it come from down-there people," he said, pointing to the regions below. "Glassie of those die in break of tunnel. We find, take this." Well, Robin thought, this adds to the evidence. There is some sort of higher civilization below. Not yet at the fire-building stage, but advancing at the dawn of the Iron Age. I wonder if this is really writing or just a design? And I wonder what metal this is? Not iron surely. He thought a while, then deciding that as a creature of magic he could get away with it, informed Korree that he would take the knife blade away with him. The Glassies seemed unconcerned. It was evident that Robin was far outside their taboos.