-- and the bird had tumbled out of the air. She'd scuttled to her knees and cupped the bird in her hands; its heart rattled as ice droplets melted from its wings.

The bird was an ice blue, a spectacular color she'd never seen before. And in its beak was a vivid orange flower.

The precise color of those strange orange splashes on the Shell.

The bird recovered and clattered away, but that didn't matter. Allel knew it must have lost its way and crossed the Gap between the worlds.

She'd run off down the heathered slopes to her home.

She dogged Lantil's footsteps as he trudged wearily among the teepees. "But if the world and the Shell are globes, what holds them apart?" Perhaps there were great pillars beyond the horizon...

Lantil pushed a lank of dirty hair back from his brow. "What does it matter?"

"I want to know," she stamped.

Her grandfather sighed. "All right." He knelt beside Allel and made a gnarled fist. "There's the world, Home, round like a ball." He cupped his other hand around the fist. "And there's the Shell, a hollow sphere around Home." Now he broke the fist and twirled a fingertip in a helix inside the cupped hand. "The Sun moves through the Gap, giving us day and night, summer and winter."

Allel nodded impatiently. "I know all that. But who built it all?"

"People, of course." He straightened up, massaging his back. "To keep out monsters called the Xeelee."

Allel, wide-eyed, imagined giants stalking beyond the Shell, beating their fists against ocean bottoms and tree roots.

"Now I've got to get on," Lantil snapped. "Get on with you, child. Get on..." Grumbling, he went back to his chores.

Allel ran off, savoring her newest fragment of knowledge. She imagined flying up to a saucer-shaped land where a world hung in the sky, a ball plastered with rocks and trees.

The next morning she rose at dawn. She pushed her way out of the teepee's bark flap, letting the gray cold scour out her night fug. She shivered her way to a cow-tree and sucked icy milk from one of its nipples.

The village was hushed in the continued absence of the warriors. A group of old folk and children were at work already, making the most of the precious summer day; they were peeling a fresh sheet of clothlike bark, barely formed, from one of the cow trees. Allel peered furtively up at the Shell. The morning terminator was a gray bar that straddled the horizons, scouring eastward. The night lands beyond were broken by flickering sparks: fires that showed that people lived on the Shell, like flies on that great ceiling.