„I was taught in school that Mesklin is a big, hollow bowl. The part where most people live is near the bottom, where there is decent weight. The philosophers have an idea that weight is caused by the pull of a big, flat plate that Mesklin is sitting on; the farther out we go toward the Rim, the less we weigh, since we’re farther from the plate. What the plate is sitting on no one knows; you hear a lot of queer beliefs on that subject from some of the less civilized races.”

„I should think if your philosophers were right you’d be climbing uphill whenever you traveled away from the center, and all the oceans would run to the lowest point,” interjected Lackland. „Have you ever asked one of your philosophers that?”

„When I was a youngster I saw a picture of the whole thing. The teacher’s diagram showed a lot of lines coming up from the plate and bending in to meet right over the middle of Mesklin. They came through the bowl straight rather than slantwise because of the curve; and the teacher said weight operated along the lines instead of straight down toward the plate,” returned the commander. „I didn’t understand it fully, but it seemed to work. They said the theory was proved because the surveyed distances on maps agreed with what they ought to be according to the theory. That I can understand, and it seems a good point. If the shape weren’t what they thought it was, the distances would certainly go haywire before you got very far from your standard point.”

„Quite right. I see your philosophers are quite well into geometry. What I don’t see is why they haven’t realized that there are two shapes that would make the distances come out right. After all can’t you see that the surface of Mesklin curves downward? If your theory were true, the horizon would seem to be above you. How about that?”

„Oh, it is. That’s why even the most primitive tribes know the world is bowl-shaped. It’s just out here near the Rim that it looks different. I expect it’s something to do with the light After all, the sun rises and sets here even in summer, and it wouldn’t be surprising if things looked a little queer. Why, it even looks as though the — horizon, you called it? — was closer to north and south than it is east and west. You can see a ship much farther away to the east or west. It’s the light.”