And a strange thing came to pass. Soon after darkness fell upon the earth and the steady drip-drop of the rain began, a musical tinkling sound was heard which grew in volume, and became a deep-toned roar, which reechoed and reverberated from the opposite hillsides until it was like melodious and long-continued thunder. For a long time the people were puzzled and a little afraid, but Burl took courage and investigated. He emerged from the concealing thicket and peered cautiously about, seeing nothing. Then he dared move in the direction of the sound, and the gleam from a dozen fireflies showed him a sheet of water pouring over a vertical cliff to the river far below. The rainfall, gentle as it was, when gathered from all the broad expanse of the mountainside, made a river of its own, which had scoured out a bed, and poured down each night to plunge in a smother of spray and foam through six hundred feet of empty space to the swiftly flowing river in the center of the valley. It was this sound that had puzzled the tribefolk, and this sound that lulled them to sleep when Burl at last came back to allay their fears. The next day they explored their new territory with a boldness of which they would not have been capable a month before. They found a single great trap-door in the earth, sure sign of the burrow of a monster spider, and Burl resolved that before many days the spider would be dealt with. He told his tribesmen so, and they nodded their heads solemnly instead of shrinking back in terror as they would have done not long since. The tribe was rapidly becoming a group of men, capable of taking the aggressive. They needed Burl's rash leadership, and for many generations they would need bold leaders, but they were infinitely superior to the timid, rabbit-like creatures they had been. They bore spears, and they had used them. They had seen danger, and had blindly followed Burl through the forest of strangled things instead of fleeing weakly from the peril. They wore soft, yellow fur about their middles, taken from the bodies of giant slugs they had slain. They had eaten much meat, and preferred its succulent taste to the insipid savor of the mushrooms that had once been their steady diet. They knew the exhilaration of brave adventure--though they had been forced into adventure by Burl--and they were far more worthy descendants of their ancestors than those ancestors had known for many thousand years. The exploration of their new domain yielded many wonders and a few advantages. The tribefolk found that the nearest ant-city was miles away, and that the small insects would trouble them but rarely. (The nightly rush of water down the sloping sides of the mountain made it undesirable for the site of an ant colony.)