God said, “Children, attend.”

You hardly needed the invitation. The Emperor was drumming his fingers on the back of the pilot’s seat, his curious black-on-black eyes not focused on you. He said, “You are both going to have to listen to me very carefully. The Mithraeum is far away, and our route is not typical. I’m about to teach you the first lesson, and this lesson will be the foundation of the most important lesson you will ever learn as a Lyctor. There will be a time for you to learn through questioning—a time for you to learn through trying and failing—but right now you’ll learn by doing exactly what I ask of you. The only other option is your destruction.”

This did not give you much pause. You were a daughter of the Locked Tomb. The option of destruction had been your constant companion since you were three years old. Ianthe, whose voice was low with barely suppressed excitement, said: “I thought there might be a stele.”

“A stele is eight feet tall, covered in the dead languages by special Fifth adepts, and continually bathed in oxygenated blood,” said Mercymorn from the pilot’s seat. “The type of thing where, if there is one on board, you say quite soon, ‘Oh, look, a stele!’”

“Thank you, elder sister, I so love to be educated,” said Ianthe.

“Where we are going there are no obelisks for a stele to hook on to,” said the Emperor, whose fingers had ceased drumming on the back of the pilot’s seat (after his Lyctor had told her God, repressively, “That’s quite annoying, thank you,”) and were now restlessly adjusting one shabby shirtsleeve. “I am taking you both through the River.”

There must have been no small measure of blank incomprehension on your faces. He said, a little abstracted now: “It’s the only way. Faster-than-light travel turned out to be a snare—the way it was originally cracked, anyway. The first method destroyed something to do with time and distance, rendering it unusable for any good purpose…”

“I’ve always thought it should be correctly managed with wormholes,” said the Saint of Joy, doing something obtuse with the controls, “or spatial dilation.”

God said, “It’s in that wheelhouse. We came up with the stele instead, and the obelisk, which are less to do with travel than they are to do with transmission. But there will be times in your future when you will have to move unfettered by needing an obelisk, and even times yet to come when you will fulfil the sacred Lyctoral duty of setting obelisks, and that means travel through the River. I like to think of it as descending into a well.”

There was a small noise of upset from the pilot’s seat. “Teacher,” said Mercy, “it is the River. There is a perfectly good water metaphor waiting for you.”

“Well, I want the idea of two depths, and I don’t want to confuse them with the idea of speed where none—”