"You win," he told Burke. "I had a dream, and it wasn't a dream. I know something about those metal globes. They've got drives in them, and they can accelerate to a hundred and sixty gees, and I don't think I'll ride one." Wryly, he told Burke what he'd experienced. "I'm not too much surprised," said Burke. "I've managed two cube-experiences myself. I figure that these cubes trained men to operate things, without training their brains in anything else. They'd make illiterates into skilled men in a particular line, so anybody could do the work a highly trained man would otherwise be needed for. In one of my two cube-dreams I was a gun-pointer on one of those machines up on the third level. In the second cube-dream I was a rocket-pilot." "No rockets in my cube," protested Holmes. "Different period," said Burke. "Maybe, anyhow. In my dream we were using rockets to fight with, and the war was close. The enemy had taken some planets off Kandu--wherever that is!--and the situation was bad. We went out of here in rockets and fought all over the sky. But then there were supplies coming from home, and fresh fighting men turning up." He stopped abruptly. "How'd they come? I don't know. But I know they didn't come in spaceships. They just came, and they were new men and we veterans patronized them. The devil! Holmes, you say the globes have a hundred-sixty-gee drive! Nobody'd use rockets if drives like that were known!" "To stay in the party," Sandy said suddenly, with something like defiance, "I tried a cube, too. And I was a sort of supply-officer. I had the experience of being responsible for supply and being short of everything and improvising this and that and the other to keep things up to fighting standard. It wasn't easy. The men grumbled, and we lacked everything. There was no fighting in my time, and there hadn't been for centuries. But we knew the Enemy hadn't given up and we had to be ready, generation after generation, even when nothing happened. And we knew that any minute the Enemy might throw something unexpected, some new weapon, at us." "History-cubes," said Keller interestedly. "Different periods. Right?" "Dammit, yes!" said Burke. "We've got accounts of past times and finished battles, but we need to know who's coming and what to do about it! Maybe the rocket-dream was earliest in time. But how could a race with nothing better than rockets ever get here? And how could they supply the building of a place like this?" There was no answer. Facts ought to fit together. When they don't, they are useless.