He considered ordering them to rebuild the city on the surface the way he had originally designed it, but after a moment’s thought decided against it. He was too busy to fool with details. Let Derec have his ecosystem, if it would keep him occupied.

He led the robots through an interchange with a wide cross-corridor, traveled that one for a while, then stepped to a slower strip to make a connection with a smaller corridor running parallel to the first. This one had only a single slidewalk running in each direction, and as they proceeded down the northbound one Avery counted doorways, at last stepping off onto static pavement in front of an unmarked door about two thirds of the way down the length of the block.

Behind that door should be his new laboratory. Avery had instructed the central computer to build it here in this thoroughly anonymous location and then forget that location-and to fend off any inquiry about it as well-hoping to keep his inquisitive son from tracking it down quite so easily as he might otherwise. Avery knew that Derec would find it eventually, but he only needed secrecy for a short while. Just long enough to take these three robots of Janet’s apart and see what made them tick.

A few hundred kilometers above him, Janet Anastasi looked out the viewscreen at much the same scene Dr. Avery and Derec had seen earlier in the day. Her reaction was considerably different from what theirs had been, however. She had been expecting the ultimate city-gone-amok, a planet despoiled and overrun by her ex-husband’s Machiavellian monstrosities, but when she found what appeared to be unspoiled wilderness, she could hardly believe her eyes. Wendell Avery had actually left something alone for once in his life? Unbelievable.

She almost regretted the errand that had taken her a week out of her way before coming here.

Her original impulse, when she’d seen the mess Wendell had made of Tau Puppis IV and the aliens who called themselves the Kin, had been to track him down and demand that he stop using her invention to meddle in alien affairs, but as soon as she’d cooled off she’d realized how futile that would be. He had never listened to her before; why should he start now? She needed a lever if she intended to move him.

She had found that lever, too, but after seeing this incredible display of ecological conscientiousness she began to have second thoughts. Perhaps she had underestimated old Stoneface. Maybe she should hold off a while and see what other changes he had undergone in the years since they had parted company.

Or was this David’s influence she saw here? Had her son grown up to be a romantic? What an interesting notion. To think that he might now be a thinking being in his own right, rather than the squalling, vomiting, excreting lump of protoplasm she had so gladly left in the care of her robots when she had made her escape from Wendy and domestic life so many years ago. An adult now. The very concept nearly boggled the mind.

Nodding, she said softly, “Yes, I think we should have a closer look at this.”

“Of course, Mistress.” The robot at her side reached out to the ship’s controls, twisted a knob, and the viewscreen began to zoom in on the mountaintops beneath them.

Wearily, she said, “No, no, Basalom, I meant the whole situation. Land and have a look around, see what they’re up to down there.”

Basalom’s humaniform face remained blank, but his lips moved silently, forming the words, See what they ’ re up to down there. He blinked, first one eye, then the other; then he nodded and smiled and said, “Of course, Mistress.”

Basalom had lately taken to nodding and smiling when he had no idea what she was talking about. Janet considered trying to explain to him what she’d meant, but she supposed his reaction was probably a defense against just such an explanation, which often as not just made things worse. He was learning. Good. That’s why she had deliberately left gaps in his programming: to see if he could fill them by using intuitive thought processes. He apparently was doing so, though not in the way she had expected.

Not surprising. Nothing about this project seemed to be going quite the way she’d expected it to.

The jungle was most dense right near the Compass Tower. As soon as they had pushed their way through the first hundred meters or so of thick underbrush, Derec and Ariel found that it gave way to more open forest floor. The reason for the change was obvious: overhead, the thick canopy of treetops all but blocked out the sun, leaving the lower layers in dim twilight. Only where the Tower penetrated the upper level did enough light come through to support a complex undergrowth.

“It’s creepy,” Ariel whispered, holding Derec’s hand tight in her left and the blanket in her right.

Derec was nearly lost in the rich blend of aromas assaulting his nostrils. Every bush, every leaf, every blossom had its own fragrance, and if he paid attention he could distinguish their individual signatures in the air. Finally Ariel’s comment penetrated his consciousness, and he frowned in puzzlement. “Creepy? It’s wonderful! I’ve never seen or felt or smelled anything like it.” He stooped down to examine the ground at the edge of the trail, pulling Ariel down with him. “Look. It goes from trees all the way down to these tiny little lichens. I bet if we had a microscope we’d even see protozoans and bacteria. I had no idea the robots would be this thorough.”

“Just what did you tell them to do, anyway?”

Derec stood and brushed his hands against his pants. A butterfly glided toward him, hovered near his face a moment, then drifted on toward Mandelbrot, who had insisted on coming along to guard them but was maintaining his distance to give them privacy. Grinning sheepishly after the butterfly, Derec said, “Well, I told them to make an ecosystem based on the information I’d gotten from the central library. I assumed they’d integrate it into the existing city; you know, make a lot of parks and open spaces and stuff like that. Instead, they did this.” He held his arms out to indicate their surroundings, then led off down the trail again.

“Have you asked why yet?”

“Oh, I know why. I wasn’t specific enough. I didn’t tell them exactly what I had in mind, so in my absence they did what they thought was safest: removed the city and reconstructed the classical biomes as thoroughly as they could. Which turns out to be pretty thoroughly, by the look of it.”

“But we’ve only been gone what-five or six months? How could they have done all this in so short a time?”

Derec had lost track of the time during their travels, but he supposed it had been about that. Ariel was right; that was an awfully short time to have created something like this. Derec didn’t know that much about trees, but the tall ones towering over their heads had to have been older than just a few months. Could the robots have created them fully grown? Did their genetic engineering capabilities extend to that?

A sudden suspicion came to him, and he stopped in the middle of the trail, looking out into the forest all around them. Ariel bumped into him from behind. “What’s the matter?” she asked.

By way of answer, Derec strode off the path toward a tree trunk, swishing through the low ferns and pushing aside vines until he reached it. It was about twice as big around as he could have encircled with his arms, arrow-straight, and covered with a rough, scaly sort of grayish bark. He swung his hand around to slap it with his open palm. The thunk was barely audible. His hand stung from the impact, but that proved nothing. Derec made a fist and punched the tree with a fair amount of force behind it. It jarred his hand and forearm, but he had pulled the punch and again the results were inconclusive.