Alvin had wandered away and was circumnavigating the central pillar. Presently his voice came to Rorden, slightly muffled and overlaid with echoes from the walls of the chamber.
“What is it?” called Rorden, not wishing to move, because he had nearly deciphered 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 towards the points of the compass. But this time not all of it was too dim to be clearly seen, for one of the lines, and one only, 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 Rorden stood gazing down at that silent symbol. To Rorden it was no more than another question for his machines, but to Alvin its promise was boundless. He tried to imagine this great chamber as it had been in the ancient days, when air transport had come to an end but the cities of Earth still had commerce one with the other. 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. He wondered how long it had gleamed there among its darkened companions, waiting to guide the steps that never came, until at last Yarlan Zey had sealed the moving ways and closed Diaspar against the world.
That had been hundreds of millions of 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.
Rorden broke into his reverie at last. He seemed a little nervous and ill at ease.
“It’s time we went back,” he said. “I don’t think we should go any further now.”
Alvin recognized the undertones in his friend’s voice, and did not argue with him. He was eager to go forward, but realized that it might not be wise without further preparation. Reluctantly he turned again toward the central pillar. As he walked to the opening of the shaft, the floor beneath him gradually clouded into opacity, and the gleaming enigma far below slowly faded from sight.