toward the walls of the chamber.
"I thought so!" he exclaimed suddenly. "Do you see how these radiating lines lead toward the small tunnels?"
Alvin had noticed that besides the great arches of the moving ways there were innumerable smaller tunnels leading out of the chamber-tunnels that sloped downward instead of up.
Kedron continued without waiting for a reply.
It would be hard to think of a simpler system. People would come down the moving ways, select the place they wished to visit, and then follow the appropriate line on the map.
"And what happened to them after that?" asked Alvin. Khedron was silent, his eyes searching out the mystery of those descending tunnels. There were thirty or forty of them, all looking exactly the same. Only the names on the map would have enabled one to distinguish between them, and those names were indecipherable now.
Alvin had wandered away and was circumnavigating the central pillar. Presently his voice came to Khedron, slightly muffled and overlaid with echoes from the walls of the chamber.
"What is it?' called Khedron, not wishing to move, because he had nearly succeeded in reading one of the dimly visible groups of characters. But Alvin's voice was insistent, so he went to join him.
Far beneath was the other half of the great map, its faint webwork radiating to the points of the compass. This time, however, not all of it was too dim to be clearly seen, for one of the lines and only one-was brilliantly illuminated. It seemed to have no connection with the rest of the system, and pointed like a gleaming arrow to one of the downward-sloping tunnels. Near its end the line transfixed a circle of golden light, and against that circle was the single word LYS. That was all.
For a long time Alvin and Khedron stood gazing down at that silent symbol. To Khedron it was a challenge he knew he could never accept-and which, indeed, he would rather did not exist. But to Alvin it hinted at the fulfillment of all his dreams; though the word Lys meant nothing to him, he let it roll around his mouth, tasting its sibilance like some exotic flavor. The blood was pounding in his veins, and his cheeks were flushed as by a fever. He stared around this great concourse, trying to imagine it as it had been in the ancient days, when air transport had come to an end but the cities of Earth still had contact with one another. He thought of the countless millions of years that had passed with the traffic steadily dwindling and the lights on the great map dying one by one, until at last only this single line remained. How long, he wondered, had it gleamed there among its darkened companions, waiting to guide the steps that never came, until Yarlan Zey had sealed the moving ways and closed Diaspar against the world?
And that had been a billion years ago. Even then, Lys must have lost touch with Diaspar. It seemed impossible that it could have survived; perhaps, after all, the map meant nothing now.
Khedron broke into his reverie at last. He seemed nervous and ill at ease, not at all like the confident and self-assured person that he had always been in the city above.
"I do not think that we should go any farther now," he said. "It may not be safe until-until we are more prepared."
There was wisdom in this, but Alvin recognized the underlying note of fear in Khedron's voice. Had it not been for that, he might have been sensible, but a too-acute awareness of his own valor, combined with a contempt for Khedron's timidity, drove Alvin onward. It seemed foolish to have come so far, only to turn back when the goal might be in sight.
"I'm going down that tunnel," he said stubbornly, as if challenging Khedron to stop him. "I want to see where it leads." He set off resolutely, and after a moment's hesitation the Jester followed him along the arrow of light that burned beneath their feet.
As they stepped into the tunnel, they felt the familiar tug of the peristaltic field, and in a moment were being swept effortlessly into the depths. The journey lasted scarcely a minute; when the field released them they were standing at one end of a long narrow chamber in the form of a halfcylinder. At its distant end, two dimly lit tunnels stretched away toward infinity.
Men of almost every civilization that had existed since the Dawn would have