 What is special about light in this story?
But its outward perils could not compare with the Ryzgas themselves, who slept within, ready to wake and conquer.... The ice-wind blew from the glacier, but Var's love was round her as a warming cloak, a cloak that glowed softly golden in the deepening twilight, even as her love was about him. For the flame that had sprung between them at the Truce of New Grass, she had challenged the feud of their peoples and had left her home, to follow him. It was starry night already when they saw the light from the Watcher's cave. Var saw with some surprise that all the walls were sheathed in ice—warm to the touch, bound fast against melting by the Watcher's will. Hot food and drink were before them almost at once. Warming to the old man now, Var sketched his and Neena's history briefly. When I had gone that far, the mountain began to shake, the force that is in the Earth rumbled below, and I returned in time." They were great and evil as no other people has been, because they wanted the stars. "Because of them we must build with dreams instead of iron, and our only fire is that of the Sun, and even now, two thousand years later, the Earth is still slowly recovering from the pangs and poison of that age. "From the memories that the old Watchers have left here, and from the memories of dead men that still echo in the air, I have gathered a picture of that world's end. Only the angry light of fires relieved the city's darkness—that, and the blue-white lightning flashes that silhouetted the naked skeletons of buildings and were followed by thunder and a shaking of the earth. From the center, over the citadel, an immense white globe soared upward, rising swiftly without sound. He was momentarily uncertain that he and she were real and here, such had been the force of the dream, a vision of such scope and reality as Var had never seen—no, lived through—before. These raised a black mountain from the Earth's heart, and in hollows within it cast themselves into deathless sleep, their deathless and lifeless sentinels round them, to wait till someone dare arouse them, or until their chosen time—no one knows surely. "I have told you the story you know, and have shown you a glimpse of the old time, because I must make sure that you do not approach the mountain in ignorance.
 It can be manipulated by the people
 It is traded like a commodity  It is the only way the adventurers nowhere to go  It can be manipulated by the people  It is liquid-like in its composition