"Forward, before the charge builds up again!" said Var. A few feet further on, they stumbled over a pile of charred bones. Someone else had made it only this far. It was farther than the Watcher had gone into these uncharted regions, and only the utmost alertness of mind and sense had saved them from death in traps like this. But as yet the way was not blocked.... Then they felt the mountain begin to tremble. A very faint and remote vibration at first, then an increasingly potent shuddering of the floor under their feet and the walls around them. Somewhere far below immense energies were stirring for the first time in centuries. The power that was in the Earth was rising; great wheels commenced to turn, the mechanical servitors of the Ryzgas woke one by one and began to make ready, while their masters yet slept, for the moment of rebirth that might be near at hand. From behind, up the tunnel, came a clear involuntary thought of dismay, then a directed thought, echoing and ghostly in the confinement of the dark burrow: "_Stop!_--before you go too far!" Var faced that way and thought coldly: "Only if you return and let us go free." In the black reaches of the shaft his will groped for and locked with that of Groz, like the grip of two strong wrestlers. In that grip each knew with finality that the other's stubbornness matched his own--that neither would yield, though the mountain above them and the world outside should crumble to ruin around them. "Follow us, then!" They plunged deeper into the mountain. And the shaking of the mountain increased with every step, its vibrations became sound, and its sound was like that of the terrible city which they had seen in the dream. Through the slow-rolling thunder of the hidden machines seemed to echo the death-cries of a billion slaves, the despair of all flesh and blood before their monstrous and inhuman power. Without warning, lights went on. Blinking in their glare, Var and Neena saw that fifty paces before them the way opened out into a great rounded room that was likewise ablaze with light. Cautiously they crept forward to the threshold of that chamber at the mountain's heart. Its roof was vaulted; its circular walls were lined with panels studded with gleaming control buttons, levers, colored lights. As they watched light flicked on and off in changing patterns, registering the progressive changes in the vast complex of mechanisms for which this must be the central control station. Behind those boards circuits opened and closed in bewildering confusion; the two invaders felt the rapid shifting of magnetic fields, the fury of electrons boiling in vacuum....