Less than a billion years had passed since the singularity here. No stars yet burned. There was virtually no iron, no carbon, no silicon -- no oxygen. Save for the helium and a few traces of more complex elements which had emerged from the singularity, there was only hydrogen. All the heavy elements would become abundant much later, when true stars began to shine and complex fusion processes in their cores got underway.

There were no Earths to land the humans on, no air for them to breathe, no metals for them to dig.

The ship unfurled its night-dark wings and dived into the hydrogen clouds. Cherry-red starbreaker beams blasted ahead of the ship; the gravity waves lanced through convection cells billions of miles wide, and a cylinder of roiling hydrogen-helium gathered. Within the cylinder temperatures rose by millions of degrees and complex fusion chains, comparable to those in the cores of the stars yet to form, were initiated.

A cascade of heavy elements emerged from the fires, and at last even a few atoms of iron were formed.

For three months the Xeelee ship patrolled the length of its creation; it passed its beautiful wings through the star-core cylinder, filtering out the heavy elements.

At last the Xeelee ship was ready to construct an Earth.

The heart of it was a core of iron seven thousand miles wide. Leaving the core at stellar-surface temperatures the ship now laid down a mantle of silicate rocks, constructed from the mineral banks it had built up, and overlaid the whole with a thin crust of oxygen and silicon. Next -- compressing billions of years of planetary evolution into weeks -- it deposited lodes of iron, bronze, tin, methane at suitably accessible points. There was even uranium. Then riverbeds, ocean floors, fjords were gouged out by the flickering of a cherry-red beam.

The process was creative; the ship almost enjoyed it.

After six months the bones of the planet were laid down. The ship landed at various points on the surface and, by firing refrigerating particle beams into the glowing sky, rapidly cooled the crust through thousands of degrees.

Next, ice asteroids were smashed into the bare surface, as were lodes of frozen oxygen and nitrogen. The ice melted and flowed into the waiting sea beds; gases hissed into a cloak about the planet.

All this took two more months; but at last the ship's night-dark wings cruised over clear oceans, through crisp blue oxygen.

The first clouds formed. Rain fell.

Next it was time to establish an ecosystem.

The ship had never visited Earth, or even the interior of the box-world its Xeelee designers had built for the humans. But it knew the general principles.

The ship's clay was the genetic material of its human occupants, and their various parasites and symbiotes. Tiny laboratories embedded in the ship's hull labored for many days.