At last they stood in a line on the rim of the world. The Edge was an arrow-straight ridge, with the two identical Faces falling away on either side. It was like standing on the roof of some huge house. Cables had been laid along the Edge; a second car clung to them. Bundles of maintenance equipment had been fixed to the surface close to the car site.

"I hope this trip was worth it," Green said, panting.

Taft barked laughter. The sound was like a dry leaf crumpling. "Well, you asked for my guidance and you got it. Obviously the stresses on the material are higher here than close to the center of a Face. So if your wonder boy is going to gain access he has as good a chance here as anywhere. Watch out for the Edge itself, though. It's sharp as a knife, down to the finest limits we can perceive."

"No," Paul said.

Green and Taft stared at him, releasing his arms. With the loss of physical contact they became still more insubstantial, receding from his vision like ghosts.

He knelt awkwardly and ran a gloved finger along the Edge. The stuff was soft; it rippled. It was like running a hand through a fine, multicolored grass.

Words like "sharp" were meaningless, of course; wooden words used by macro-men.

Green had given him the language to understand what he was perceiving: that this was the fundamental level of reality, the grain of quantum-mechanical probability wave functions.

An event was like a stone thrown into a pond; probability functions -- ripples of what-might-be -- spread out through space and time. Macro-men might see the pale shadows where the waves were thickest.

And that was all.

Their hard language of "particles" and "waves" and "here" and "now" reflected their limited perception, stony words to describe shadows. But he, Paul, the boy with no past, could sometimes see the entire surface of the pond -- and even catch hints of the depths which lay below.

He watched wave functions ripple away from the Edge, diminishing softly into prismatic shades of improbability, and felt his consciousness drawn out like a sword from its scabbard. He looked down at his body, bent awkwardly in its ill-fitting pressure suit; at the two stick men standing over it, obviously blind to the kaleidoscopic probability sparkles all around them.

The Face of the Sugar Lump was a window. He drifted through it.

He floated like a snowflake, wafted by probability winds. The Sugar Lump was full of wonders.

Here was an array of crystals which would grow at a touch into a fleet of a thousand night fighters, unfurling glistening wings like dark butterflies. Twist this flowerlike artifact just so and a city would unfold in a storm of walls and ceilings. Point this other at a star -- and watch it collapse softly into nova.

And here, rank on rank of shadowy forms, were Xeelee themselves, features smoothed-over and indistinct, embryonic.