“How could we make it worse?” Cassandra said. “People can’t live down there. Nothing can, not even bacteria. Surely that’s as bad as it gets.”

“We scored today,” Auger said. “We came back with a piece of the past—a window into history. But there’s a lot more down there we haven’t found yet. Gaps in our knowledge waiting to be filled. There’s so much we forgot, so many things we’ll never know unless we find the truth down there, preserved under the ice.”

“The Polity plans don’t threaten any of that.”

“Not on paper, no, but we all know that the plans are only a prelude. Clean up the furies and stabilise the climate, then we can begin the real work: terraforming.” She said the last word with exquisite distaste.

As the clouds thickened around the rescue crawler, Auger caught a brief glimpse of the sinuous track of the Seine, a flawless ribbon of white ice dotted here and there with cordoned dig sites. Further away, picked out in darkling glints from hovering airships, she made out the lower two-thirds of the Eiffel Tower, bent to one side like a man struggling against a gale.

“Is it such a crime to want to make the Earth liveable again?” Cassandra asked.

“In my book it is, because we can’t do it without erasing everything down there, severing every single thread back to the past. It’s like whitewashing the Mona Lisa when there’s a blank canvas next door.”

“So you advocate the terraforming of Venus instead?”

Auger felt close to tearing out her hair. “No, I don’t advocate that, either. It’s just that if I’m forced into making a choice…” She shook her head. “I don’t know why I’m having this conversation with you, of all people!”

“Why wouldn’t you?”

“Because you’re one of us, Cassandra—a good little Thresher, a good little citizen of the USNE. You’re even studying to work under Antiquities. I shouldn’t have to explain any of this stuff to you.”