One of the other pupils made a loud amused noise. "Whoever heard of a city without a roof?" he demanded. "Could lights be seen through a roof?" Rofan was embarrassed, and he remained very quiet for a while, wondering how he could have made such a stupid error. Of course lights could not be seen through a roof. And who had ever heard of a city without a roof! Thak, paying no attention to the byplay, focused his lens with great care. The students gathered about the concave bowl of white quartz. The lights were lowered, and into the bowl moved a blurred sphere. As Thak's tentacles moved the lenses closer and closer into focus, the sphere resolved itself with more and more clarity, until it was a fine image of the third planet. Awed by the splendor of the sight, the students could only stare. And indeed it was a breathtaking spectacle, as if they were gathered in the immense void of space itself, looking at the planet from a height of several thousand miles. There were five continents in two major land masses, Thak had told them. In addition, there were several islands of great size, at last one being practically of continental dimensions, besides a host of islands large and small which dotted the surface of the planet. The hemisphere on which they gazed was mostly water. The larger land mass was passing from sight. And half of the smaller mass was presented to their vision, a double continent that spread almost from pole to pole, with a narrow isthmus joining north and south. Like all Martians, they thrilled to a scene of fearful beauty, and they stood around the quartz bowl for a long time, not speaking, merely watching the twin continents come into full view. None noticed old Thak's eyes peering desperately at the image of the third planet. Nor did they see the look of utter despair that grew in his face. They were too intent on the strange scene. * * * * * It was Rofan who first felt that something was wrong. The novelty was wearing off, and an elusive thought made him uncomfortable. Something was wrong with the picture ... what was it? Suddenly he realized. He turned to Thak. "But--the lights, _Mor_ Thak? The signals--" Thak's face looked as old as Mars itself as he gazed at his pupil. He started to speak several times before he could manage. "We have failed," he said, in heavy tones. "Our signals must have been too weak for the beings of the blue planet to detect. I had hoped--" He arose and looked sadly into the evening sky. "I had hoped I was wrong. For two years now--our years--I have watched through my small telescope, and the lights have been disappearing, one by one, sometimes, but more often several at a time. I thought it was the weakness of my instrument. I was wrong. Every light on the blue planet has been blacked out..." His voice was a low wail. "_And--the blacking out of those lights means a blackout of life on Mars. A planet-wide blackout...._"