"The world bends," Cuthbert explains. "Hold a moment--"

He rolls to his feet, careful not to push off from the Lion's side, and goes to rummage in his pack. "Ha, knew I brought it!" As he come back to resume his seat, he tosses Caspian the wiggly-stranded ball that Lilly had given him. Susan laughs. "Why did'ee bring that along, 'Bert?"

"Good thing I did," he counters, amused. "Look there - if each of those strands is a person standing on a round world, and the end of each is their head, then for them it's always 'up' from the center they're standing on, see it?" He leans forward across Susan, snagging a blade of grass as he does, and draws the tip of it in the air over the koosh ball. "And if that's how a plane flies, when it lands again, it's 'up' too, because the world spins on beneath it while it's in the air above."