Mark Rogers was a prospector, and he went to the asteroid belt looking for radioactives and rare metals. He searched for years, never finding much, hopping from fragment to fragment. After a time he settled on a slab of rock half a mile thick.

Rogers had been born old, and he didn't age much past a point. His face was white with the pallor of space, and his hands shook a little. He called his slab of rock Martha, after no girl he had ever known.

He made a little strike, enough to equip Martha with an air pump and a shack, a few tons of dirt and some water tanks, and a robot. Then he settled back and watched the stars.

The robot he bought was a standard-model all-around worker, with built-in memory and a thirty-word vocabulary. Mark added to that, bit by bit. He was something of a tinkerer, and he enjoyed adapting his environment to himself.

At first, all the robot could say was "Yes, sir," and "No, sir." He could state simple problems: "The air pump is laboring, sir." "The corn is budding, sir." He could perform a satisfactory salutation: "Good morning, sir."

Mark changed that. He eliminated the "sirs" from the robot's vocabulary; equality was the rule on Mark's hunk of rock. Then he dubbed the robot Charles, after a father he had never known.

As the years passed, the air pump began to labor a little as it converted the oxygen in the planetoid's rock into a breathable atmosphere. The air seeped into space, and the pump worked a little harder, supplying more.

The crops continued to grow on the tamed black dirt of the planetoid. Looking up, Mark could see the sheer blackness of the river of space, the floating points of the stars. Around him, under him, overhead, masses of rock drifted, and sometimes the starlight glinted from their black sides. Occasionally, Mark caught a glimpse of Mars or Jupiter. Once he thought he saw Earth.