_A long time later the voice in his helmet spoke again, and he relaxed, and lifted the helmet. He nodded to the others of the crew of this weapon. Then a trumpet blew again, and he dismounted leisurely from the saddle of the ungainly thing he'd fired, and he and his companions waited while long lines of men filed stolidly past the doorway. They were on the way back to the bunk-rooms. They did not look well-fed. His turn came. His crew filed out into the corridor, now filled with men moving in a bored but disciplined fashion. He heard somebody say that it was an Enemy scout, trying some new device to get close to the fortress. Eight weapons had fired on it at the same instant, his among them. Whatever the new device was, the Enemy had found it didn't work. But he knew that it needn't have been a real Enemy, but just a drill. Nobody knew when supposed action was real. There was much suspicion that there was no real action. There was always the possibility of real action, though. Of course. The Enemy had been the Enemy for thousands of years. A century or ten or a hundred of quietude would not mean the Enemy had given up...._ * * * * * Then Burke found himself staring at the quietly glowing monitor-lights of his own ship's control-board. He was himself again. He remembered opening his eyes. He'd dozed, and he'd dreamed, and now he was awake. And he knew with absolute certainty that what he'd dreamed came from the black cube he'd brought back from the previously locked-up room. But there was a difference between this dream and the one he'd had for so many years. He could not name the difference, but he knew it. This was not an emotion-packed, illusory experience which would haunt him forever. This was an experience like the most vivid of books. It was something he would remember, but he would need to think about it if he were to remember it fully. He sat stiffly still, going over and over this new memory, until he heard someone moving about in the compartment below. "Sandy?" "Yes," said Sandy downstairs. "What is it?" "I opened the door that bothered Pam," said Burke. Suddenly the implications of what had just occurred began to hit him. This was the clue he'd needed. Now he knew--many things. "I found out what the fortress is for. I suspect I know what the signals were intended to do." Silence for a moment. Then Sandy's voice. "I'm coming right up." In minutes she ascended the stairs. "What is it, Joe?" He waved his hand, with some grimness, at the small black object on the control-desk. "I found this and some thousands of others behind that creepy door. I suspect that it accounts for the absence of signs and symbols. It contains information. I got it. You get it by dozing near one of these things. I did. I dreamed." Sandy looked at him anxiously.