«The people of the south could tell us more. I have some friends there; I will call them in the morning.»

Alvin scarcely heard him; he was deep in his own thoughts, trying to remember all that he had ever heard of Shalmirane. It was little enough after this immense lapse of time, no one could tell the truth from the legend. All that was certain was that the Battle of Shalmirane marked the end of Man’s conquests and the beginning of his long decline.

Among those mountains, thought Alvin, might lie the answers to all the problems that had tormented him for so many years.

«How long,» he said to Hilvar, «would it take us to reach the fortress?»

«I’ve never been there, but it’s much farther than I intended to go. I doubt if we could do it in a day.»

«Can’t we use the ground-car?»

«No; the way lies through the mountains and no cars can go there.»

Alvin thought it over. He was tired his feet were sore, and the muscles of his thighs were still aching from the unaccustomed effort. It was very tempting to leave it for another time. Yet there might be no other time.

Beneath the dim light of the failing stars, not a few of which had died since Shalmirane was built, Alvin wrestled with his thoughts and presently made his decision. Nothing had changed; the mountains resumed their watch over the sleeping land. But a turning point in history had come and gone, and the human race was moving toward a strange new future.

Alvin and Hilvar slept no more that night, but broke camp with the first glow of dawn. The hill was drenched with dew, and Alvin marveled at the sparkling jewelry which weighed down each blade and leaf. The «swish» of the wet grass fascinated him as he plowed through it, and looking back up the hill he could see his path stretching behind him like a dark band across the shining ground.

The sun had just lifted above the eastern wall of Lys when they reached the outskirts of the forest. Here, Nature had returned to her own. Even Hilvar seemed somewhat lost among the gigantic trees that blocked the sunlight and cast pools of shadow on the jungle floor. Fortunately the river from the fall flowed south in a line too straight to be altogether natural and by keeping to its edge they could avoid the denser undergrowth. A good deal of Hilvar’s time was spent in controlling Krif, who disappeared occasionally into the jungle or went skimming wildly across the water. Even Alvin, to whom everything was still so new, could feel that the forest had a fascination not possessed by the smaller, more cultivated woods of northern Lys. Few trees were alike; most of them were in various stages of devolution and some had reverted through the ages almost to their original, natural forms. Many were obviously not of Earth at all-probably not even of the Solar System. Watching like sentinels over the lesser trees were giant sequoias, three or four hundred feet high. Once they had been called the oldest things on Earth; they were still a little older than Man.

The river was widening now; ever and again it opened into small lakes, upon which tiny islands lay at anchor. There were insects here, brilliantly colored creatures swinging to and fro over the surface of the water. Once, despite Hilvar’s commands, Krif darted away to join his distant cousins. He disappeared instantly in a cloud of glittering wings, and the sound of angry buzzing floated toward them. A moment later the cloud erupted and Krif came back across the water, almost too quickly for the eye to follow. Thereafter he kept very close to Hilvar and did not stray again.

Toward evening they caught occasional glimpses of the mountains ahead. The river that had been so faithful a guide was flowing sluggishly now, as if it too were nearing the end of its journey. But it was clear that they could not reach the mountains by nightfall; well before sunset the forest had become so dark that further progress was impossible. The great trees lay in pools of shadow, and a cold wind was sweeping through the leaves. Alvin and Hilvar settled down for the night beside a giant redwood whose topmost branches were still ablaze with sunlight.

When at last the hidden sun went down, the light still lingered on the dancing waters. The two explorers-for such they now considered themselves, and such indeed they were -lay in the gathering gloom, watching the river and thinking of all that they had seen. Presently Alvin felt once again steal over him that sense of delicious drowsiness he had known for the first time on the previous night, and he gladly resigned himself to sleep. It might not be needed in the effortless life of Diaspar, but he welcomed it here. In the final moment before unconsciousness overcame him, he found himself wondering who last had come this way, and how long since.

The sun was high when they left the forest and stood at last before the mountain walls of Lys. Ahead of them the ground rose steeply to the sky in waves of barren rock. Here the river came to an end as spectacular as its beginning, for the ground opened in its path and it sank roaring from sight. Alvin wondered what happened to it, and through what subterranean caves it traveled before it emerged again into the light of day. Perhaps the lost oceans of Earth still existed, far down in the eternal darkness, and this ancient river still felt the call that drew it to the sea.

For a moment Hilvar stood looking at the whirlpool and the broken land beyond. Then he pointed to a gap in the hills. «Shalmirane lies in that direction,» he said confidently. Alvin did not ask how he knew; he assumed that Hilvar’s mind had made brief contact with that of a friend many miles away, and the information he needed had been silently passed to him.

It did not take long to reach the gap, and when they had passed through it they found themselves facing a curious plateau with gently sloping sides. Alvin felt no tiredness now, and no fear-only a taut expectancy and a sense of approaching adventure. What he would discover, he had no conception. That he would discover something he did not doubt at all.

As they approached the summit, the nature of the ground altered abruptly. The lower slopes had consisted of porous, volcanic stone, piled here and there in great mounds of slag. Now the surface turned suddenly to hard, glassy sheets, smooth and treacherous, as if the rock had once rump molten rivers down the mountain.

The rim of the plateau was almost at their feet. Hilvar reached it first, and a few seconds later Alvin overtook him and stood speechless at his side. For they stood on the edge, not of the plateau they had expected, but of a giant bowl half a mile deep and three miles in diameter. Ahead of them the ground plunged steeply downward, slowly leveling out at the bottom of the valley and rising again, more and more steeply, to the opposite rim. The lowest part of the bowl was occupied by a circular lake, the surface of which trembled continually, as if agitated by incessant waves.

Although it lay in the full glare of the sun, the whole of that great depression was ebon black. What material formed the crater, Alvin and Hilvar could not even guess, but it was black as the rock of a world that had never known a sun. Nor was that all, for lying beneath their feet and ringing the entire crater was a seamless band of metal, some hundred feet wide, tarnished by immeasurable age but still showing no slightest sign of corrosion.

As their eyes grew accustomed to the unearthly scene, Alvin and Hilvar realized that the blackness of the bowl was not as absolute as they had thought. Here and there, so fugitive that they could only see them indirectly, tiny explosions of light were flickering in the ebon walls. They came at random, vanishing as soon as they were born, like the reflections of stars on a broken sea.

«It’s wonderful!» gasped Alvin. «But what is it?»

«It looks like a reflector of some kind.»