“That photogram was taken with a standard silver nitrate emulsion,” Lord Asriel said. “I’d like you to look at another one, taken from the same spot only a minute later, with a new specially prepared emulsion.”

He lifted out the first slide and dropped another into the frame. This was much darker; it was as if the moonlight had been filtered out. The horizon was still visible, with the dark shape of the hut and its light snow-covered roof standing out, but the complexity of the instruments was hidden in darkness. But the man had altogether changed: he was bathed in light, and a fountain of glowing particles seemed to be streaming from his upraised hand.

“That light,” said the Chaplain, “is it going up or coming down?”

“It’s coming down,” said Lord Asriel, “but it isn’t light. It’s Dust.”

Something in the way he said it made Lyra imagine dust with a capital letter, as if this wasn’t ordinary dust. The reaction of the Scholars confirmed her feeling, because Lord Asriel’s words caused a sudden collective silence, followed by gasps of incredulity.

“But how-”

“Surely-”

“It can’t-”

“Gentlemen!” came the voice of the Chaplain. “Let Lord Asriel explain.”

“It’s Dust,” Lord Asriel repeated. “It registered as light on the plate because particles of Dust affect this emulsion as photons affect silver nitrate emulsion. It was partly to test it that my expedition went north in the first place. As you see, the figure of the man is perfectly visible. Now I’d like you to look at the shape to his left.”

He indicated the blurred shape of the smaller figure.

“I thought that was the man’s daemon,” said the Enquirer.

“No. His daemon was at the time coiled around his neck in the form of a snake. That shape you can dimly see is a child.”

“A severed child-?” said someone, and the way he stopped showed that he knew this was something that shouldn’t have been voiced.

There was an intense silence.

Then Lord Asriel said calmly, “An entire child. Which, given the nature of Dust, is precisely the point, is it not?”

No one spoke for several seconds. Then came the voice of the Chaplain.

“Ah,” he said, like a thirsty man who, having just drunk deeply, puts down the glass to let out the breath he has held while drinking. “And the streams of Dust…”

“-Come from the sky, and bathe him in what looks like light. You may examine this picture as closely as you wish: I’ll leave it behind when I go. I’m showing it to you now to demonstrate the effect of this new emulsion. Now I’d like to show you runescape gold farminganother picture.”

He changed the slide. The next picture was also taken at night, but this time without moonlight. It showed a small group of tents in the foreground, dimly outlined against the low horizon, and beside them an untidy heap of wooden boxes and a sledge. But the main interest of the picture lay in the sky. Streams and veils of light hung like curtains, looped and festooned on invisible hooks hundreds of miles high or blowing out sideways in the stream of some unimaginable wind.

“What is that?” said the voice of the Sub-Rector.

“It’s a picture of the Aurora.”