On the fourth floor, they entered a large room filled with reading cubicles, each with a viewer and a flat gray panel mounted in a small desk. One of the desks had been equipped with a recently imported Tensor lamp connected to the new power supply. Lanier pulled out a chair for her. She sat.

"I'll be back in a moment," he said. He walked to the opposite side of the room, passed through a door and left her alone. She fingered the viewer on the desk—was it for video, microfilm? She couldn't tell. The screen was flat and black as ebony, no more than a quarter of an inch thick.

There was something unusual about the chair. A small cylinder was mounted horizontally in the middle of the seat, fitting with some discomfort between her buttocks. There might have been cushions at one time, covering the cylinder—or perhaps the chair created its own cushion when powered up.

Patricia glanced nervously at the rows of empty cubicles, trying to imagine those who had last used them. When Lanier returned, she was very glad to see him. Her hands were trembling.

"Spooky," she said, smiling weakly.

He held out a small book bound in milky plastic. She thumbed through the pages. The paper was thin and tough. The language was English, though the typeface was unusual—too many serifs. She opened to the title page.

"Tom Sawyer," she read, "by Samuel Langhorne Clemens, Mark Twain." The publication date was 2110. She closed the book and put it down, swallowing hard.

"Well?" Lanier asked softly.

She looked up at him, frowning. Then a kind of understanding passed between them. She opened her mouth to speak and shut it again.

"You've wondered why I'm so tired looking," Lanier said.

"Yes."

"Do you understand, now?"

"Because of this. . . library."

"Partly," he said.

"It's from the future. The Stone is from our future.

"We're not certain of that," he said.

"But that's why I'm here. . . to help you figure out how."

"There are other puzzles, equally mystifying, and perhaps they all tie together."

She opened the book again. "Published by Greater Georgia General, in cooperation with Harpers of the Pacific."

He reached down and took the book from her hands. "That's enough for now. We'll go outside. You can rest for a bit, or we can spend a couple of hours at the security base."

"No," she said. "I want to go on." She closed her eyes for a few seconds. He left to reshelve the book, then returned and walked ahead of her to the ground floor.

"The subway entrance is two blocks from here," he said. "We can walk it. Exercise clears the head."

She followed him across one corner of the park, looking at without really seeing the buildings and their signs in the various languages of Earth, knowing she was past the point of assimilation.

They passed beneath a half-moon arch and walked down a double-back incline into the subway station.