“Right.” Now three of Mrs. Flowers’s fingers go up. “What is the lifespan of a genetically optimal human under mission conditions?” The question goes into the slot; a half-dozen documents of various sizes fly off shelves and flutter over.

114 years, reads one.

116 years, reads a second.

119 years, reads a third.

Mrs. Flowers bends to scratch the ears of the dog at her feet. All the while she watches Konstance. “Now you know the Argos’s velocity, the distance it needs to travel, and the expected lifespan of a traveler under these conditions. Last question. How long will our journey take?”

Konstance stares at the desk.

“Use the Library, dear.” Again Mrs. Flowers taps the slot with one fingernail. Konstance writes the question on a sheet of paper and drops it in the slot, and as soon as it vanishes a single slip of paper emerges high in the barrel vault, drifting down, seesawing back and forth like a feather, and lands in front of her.

“216,078 Earth days.”

Mrs. Flowers watches her, and Konstance gazes down the length of the vast atrium to where the shelves and ladders converge in the distance, and a glimmer of understanding rises, then sinks away again.

“How many years is that, Konstance?”

She looks up. A flock of digital birds passes above the barrel vault, and below that a hundred books and scrolls and documents crisscross the air at a hundred different altitudes, and she can feel the attention of others in the Library on her. She writes 216,078 Earth days in years? and puts the paper in and a fresh slip flutters down.

592.

The pattern of woodgrain on the surface of the desk is churning now, or appears to be, and the marble floor tiles are swirling too, and something roils in her gut.

It takes everyone together,

Everyone together…

Five hundred and ninety-two years.

“We’ll never—?”

“That’s right, child. We know that Beta Oph2 has an atmosphere like Earth’s, that it has liquid water like Earth does, that it probably has forests of some type. But we will never see them. None of us will. We are the bridge generations, the intermediaries, the ones who do the work so that our descendants will be ready.”

Konstance presses her palms to the desk; she feels as though she might black out.

“The truth is a great deal to absorb, I know. That’s why we wait to bring children to the Library. Until you are mature enough.”

Mrs. Flowers lifts a slip of paper from the box and writes something. “Come, I want to show you one more thing.” She tucks the paper into the slot and a tattered book, as wide and as tall as the entrance to Compartment 17, lurches off a second-floor shelf, gives a few inelegant flaps, and lands open in front of them. Its pages are profoundly black, as though a doorway has been opened on the rim of a bottomless pit.