“I understand that you have to select which information is relevant, but you can surely be more helpful than you’ve been up to now.”

“We’ve been very helpful,” said the ship’s computers. “You’re alive, aren’t you?”

“Loaf is wearing a facemask!”

“He is alive, your whole group is alive, and you are in control of this ship.”

Am I? wondered Rigg. “I order you to tell me how much control I will have over the Wall after I leave here.”

“If you place all the jewels into the control field, and all the ships accept your command, and if you then take the jewels with you and keep them on your person, you will be able to command that any Wall go up or down as you choose.”

“Even if the consequences might be dangerous?”

“If you’re accepted as commander of a ship, it’s your decision.”

Rigg thought for a while. “Can I change the nature of the Wall?”

“The Wall cannot be anything other than what it is.”

Wrongly worded question or final answer? Rigg couldn’t be sure without probing more. “The Wall creates a very intense field. Can I change its intensity?”

“Yes,” said the voice.

“The Wall has different effects. It gives us languages, for instance.”

“There is a stimulant field coterminous with the Wall that prepares your brain to accept and produce all the phonemes, morphemes, and memes of all the languages ever spoken within a given wallfold.”

“So the languages are contained in the Wall.”

“Languages can only exist in the human mind.”

Rigg sighed. “This stimulant field that is coterminous with the Wall has enough information about languages spoken within the wallfold that it can prepare any human brain to understand and produce the language as if it were the person’s native language.”

“Yes.”

“Is there any limit to the number of languages a person can know?”

“No.”

“But humans can’t learn that many languages.”

“True,” said the voice.

Rigg wanted to demand the answer to the contradiction, but then he remembered that Father was listening, and he knew that Father would make him figure out a resolution to the contradiction by himself. “So learning a language is harder than knowing one.”

“There is no limit to the number of ways of making language that a human brain can know, but since language acquisition takes time, even for young children, there is a definite limit to the number of languages that can be learned.”

“What about vocabulary? How did I know the words to use when I talked to those ancient people who were watching the battle outside the city?”

“They were supplied to you by the stimulant field as you needed them, according to the meaning you were attempting to express.”

“This field can read my mind?”

“It evaluates the conversation and makes available to you the full range of vocabulary needed to achieve communication between you and the other person, with words made more available according to their likelihood of being needed for the topic at hand.”

Rigg was fascinated by the idea that an invisible field could anticipate the words he would need. But he must not let himself be distracted by his intense curiosity about these phenomenal machines. Instead, he forced himself to get back to the subject at hand. Whatever that was, or should be—he didn’t even know what it was important for him to think about.

“The humans from Earth. They built this ship, so all these machines and fields and all, they created them.”

“Yes.”

“So how can I guess what they’ve gone on and created in the eleven thousand years since—”

“Ram says to tell you that you’re being stupid.”

“Eleven years, not eleven thousand,” said Rigg, catching his error at once. “This ship arrived here eleven thousand years ago, but it left Earth only eleven years ago. So their technology won’t have advanced all that much over what you have here.”

“That might lead you to false assumptions. They did not supply this ship with all the technology they knew. They equipped us only with the technology that they believed we’d need.”

“So they have machines that you don’t have.”

“Including weapons,” said the voice.

“But why would they think they need weapons if they think we only arrived here eleven years ago?”

“We don’t know whether they were able to detect the temporal displacement,” said the voice. “They might think they’re coming to face a version of humanity that has had more than eleven thousand years of technological development since the two branches diverged.”

“Are they right? Is there any wallfold that maintained this level of technology? Or surpassed it?”

“There are wallfolds where technology is very advanced,” said the voice. “But none of the wallfolds started with this technology and built on it.”

“Why not?”

“Because we did not want any wallfold to develop the field technology that would allow them to bring down the Wall.”

Oh. That made sense.

“And we could not allow any wallfold to develop starflight and run the risk of encountering the human race on Earth before it was ready to receive visitors from another world.”

“Why not?” asked Rigg.

“Because we know that we did not,” said the ship. “In our timestream, humans from Garden never made any contact with Earth prior to the launching of this ship. Therefore we could not allow starflight to develop.”

“So you gave us eleven thousand years of development, but made sure we did not develop,” said Rigg.

“In certain areas.”

“But those might be precisely the areas where it was most important for us to develop if we were going to counter a threat from Earth,” said Rigg.

“Ram suggests that we say, ‘Now you’re thinking, Rigg.’ He also suggested that we tell you he suggested it.”

Rigg couldn’t help it. Angry as he was at his father—and he was very angry—a bit of praise from him still had the power to suffuse him with warmth and pride. He hated it that a machine had that kind of power over him. At the same time, he longed to see his father and sit down and talk with him, instead of this disembodied voice.

“What would you advise me to do right now?”

“Take control of all the other wallfolds,” said the voice.

“And then what?”

“Make your own decisions.”

“Then I’ll decide to go back in time and prevent that facemask from getting Loaf.”

“But that would prevent you from entering this room and having this conversation,” said the voice.

“You could still tell me all this without my coming here. You could have Vadesh tell me when we first meet him.”

“We cannot go back in time,” said the voice. “If you prevent yourself from coming here, you won’t be in command of this starship, and none of the commands you give us now will be in force back then.”

This was so obvious that Rigg was embarrassed that he had not thought of it. But time control was still so new to him that it was impossible for him not to revert to the normal human way of thinking about time.

“You want it this way,” said Rigg. “You want Loaf to have the facemask.”

“Vadesh needed to know how his new human-adapted facemask would work. And we needed you to know.”

“But it’s a monstrous, terrible, evil thing to do to my friend,” said Rigg. “I can’t allow that to remain in place when it’s in my power to eliminate it.”

“Now you know why the humans from Earth will be dangerous to the people of Garden,” said the voice.

“No, I don’t know,” said Rigg. “I don’t know anything.”

But even as he spoke, he understood the point that the voice—that Father—was making. The same revulsion and fear that Rigg felt about the facemask might be felt by the people of Earth when they learned about what Rigg and Umbo and Param could do with the flow of time. Fear, revulsion, rejection. And there might be things in the other wallfolds that Rigg didn’t know about yet, things that would make the facemask look like a cute pet.