Once, I fancied that they were in movement--creeping, crawling, one upon the other. And that all the wall was unsolid. A thing of slow, ponderous movement. I became suddenly aware that once more my viewpoint had abruptly changed. I had envisaged us as a tiny ship, hanging in a great dark void, with dark round things at some inconceivable distance. And then I saw it was not so. We were a tremendous ship! These round objects were tiny particles. Close at hand. Dark, yet glowing. Moving, sliding one upon the other with a suggestion of fluidity. Nor were they just here in this one direction. With my face against the window I could see them overhead. And below. And across the near-by corridor of the ship, a window there showed them the same on that side. From everywhere they crowded us. Abruptly it seemed that we were not in a void, but in a narrow, confined area with these particles jostling us. They were all of a size--all of a similar aspect. Tiny things, with space between them. Flowing like a fluid as we pushed our way among them. Drake said, "They are molecules, Frank. The molecules of the rock fragment. We'll soon enter one--and then enter our atom." I did not answer him. My thoughts went winging off. Millions of molecules here. Millions? Countless myriads. They shifted and crawled; jostled; swept past, and away. Then there seemed a darkness as of an empty void. But always I saw them again. The scene was always changing. Open space now, with banks like clouds of the clustering molecules in the distance. I fixed my attention upon one such cloud. It was coming rapidly nearer--or perhaps we were speeding toward it. A luminous cloud. It came up and went past. The molecules were huge and few. I thought perhaps in that group there were not more than thirty. Clouds speeding, with dark voids between. Why, this was space! Gigantic space here. Then I saw just two of the round things jostle past. And then some which went by all alone. Giant things now, glowing, unsolid! I began to think I could see that still other, smaller particles were clinging together to form each of these unsolid molecules. I saw one go past, and caught a glimpse of what seemed empty space within its luminous outline--and then I could almost fancy I saw the atoms, a whirling swarm of them clustering to make this unsolid outline. Drake's words rang in my thoughts. Enter one of these molecules? Find our atom? I said, "Drake, how can this ship be guided? How in Heaven's name can we--"