It was already pointed in the right direction, and in less than half a minute--the second time within fifteen minutes for me--we were deep in the Big Grayness, with the walls of the aerators looming up on both sides of us. Up above all of the sunlight had dwindled to the vanishing point and the gigantic artificial cavern was lighted now along its entire length by cold light lamps embedded in the walls at fifty-foot intervals. The solid, three-dimensional world outside our minds, whatever segment of reality we happen to be passing through, never looks quite the same to any two individuals. It is always, in a sense, a special creation, colored and altered by the human imagination. To me the cold light lamps were chillingly like enormous eyes, keeping us under constant scrutiny. The scrutiny of giants, standing motionless in shadows, with just their luminous eye-sockets visible. It was as if any moment, promoted by some wild whim, the giant forms might take a violent dislike to us, might raise mace-like metal fists and smash the tractor, very much as a robot giant had smashed a Wendel agent in space, with a fiendishly mechanical rancor. But to the frail man at my side the aerator walls may have been chilling in a quite different way, if he was giving the Big Grayness any thought at all. Apparently he wasn't, because when his voice rose above the rumble of the treads he didn't once mention the aerators or the pale blue light that was glimmering on the hood of the tractor. "It's the beginning of the end--either one way or the other," he shouted. "Either Wendel will be destroyed by the Colonists themselves for committing mass murder, or we'll go down under a juggernaut that can't be stopped. Sometimes you can't smash absolute evil, when it's backed up by absolute power." I raised my voice as high as he'd done, because I wanted to be sure he'd hear me. "It will always be stopped in the end, I think--if you have enough moral courage. That's a dynamic in itself, the most formidable of all weapons. All history confirms it." "I wish I could believe that!" he shouted back. "But I'm not so sure. And you have to fight with reasonably clean hands. Endicott is almost as guilty as Wendel, except that it would rather be destroyed than resort to mass murder." "That's two-thirds of the right," I shouted back. "That's where the biggest dividing line comes. Every tyranny in human history that has resorted to mass murder has gone down into everlasting night and darkness and very quickly. The few that survived to die a natural death drew back at that point. The great, utterly ruthless destroyers always perish."