"We've got snatches of information," said Burke. "But we don't know who built this fort, or why, except that there was a war that lasted thousands of years, with pauses for centuries between battles." He waved a hand irritably. "The Enemy tries to think up new weapons. They do. They try them. So far, they've been countered. But we're not prepared to fight a new weapon. Maybe the fort is set to battle old ones, but we don't know how to use it even for that! We've got to--" "I think--" began Keller. "I'd give plenty for a service manual on the probably useless weapons we do have," said Burke angrily. "Incidentally, Keller just found what may be an explanation of how and why this place was abandoned." Keller said suddenly, "Where would service manuals be?" He moved, almost running, toward the air-lock. Burke started to swear, and stopped. "A service-and-repair manual," he snapped, "would be near the equipment it described. How many little shelves with boxes on them have we seen? They're just the right size to hold cubes! And where are they? Next to those fighting machines next to the door of the room where the ten-foot globes are! There's a shelf of them in the instrument-room! Let's find out how to fight with this misbegotten shell of a space-fort! There'll be no help coming to us, but if the Enemy's held off for thousands of years while this civilization fell apart, we might as well try to hold it together for a few minutes or seconds longer! Let's go get some real instruction-cubes!" Keller was already gone. The others followed. Once they saw Keller in the far, far distance, hastening toward the instrument-room. Behind him, after almost running down the long corridor, Burke swung into the room where hundreds of ten-foot metal globes waited for the fortress to be remanned and to go into action again. Inside the door he found the remembered shelf, with two small boxes fastened to it. He pulled down one box and opened it. There was a black cube inside it. He thrust it upon Holmes. "Here!" he said feverishly. "Find out how those globes work! Find out what's in them, how they drive!" He ran. To the end of the corridor and up the ramp and past the supposed bunk-rooms and mess-halls. Up to the level where the ugly metal machines stood, each in its separate cubicle. There were little shelves inside each door. Each shelf contained a single box. Burke took one, two, and then stopped short. "They'll be practically alike," he muttered. "No need." He put one back. And then he felt almost insanely angry. One would need at least to be able to doze, to make use of the detailed, vivid, and utterly convincing material contained in the black cubes. And how could any man doze or sleep for the purpose of learning such desperately needed data? He'd need almost not to want the information to be able to sleep to get it! Sandy and Pam overtook him as he stood in harried frustration with a black cube in his hands.