“Five hundred years ago, a while after the Cacotopic Stain opened, there was a mild Torque storm that swept down from somewhere at sea, in the north-east. It hit New Crobuzon for a while.” Isaac shook his head slowly. “Nothing in the league of Suroch, obviously, but still enough for an epidemic of monstrous births and some very strange tricks of cartography. All the affected buildings were pulled down sharpish. Very sensible in my view. That’s when they drew up plans for the cloudtower—didn’t want to leave the weather to chance. But that’s broke now, and we’re fucked if we get any more random Torque currents. Fortunately, they seem to be getting rarer and rarer over the centuries. They sort of peaked around the 1200s.”

Isaac waved his hands at Yagharek, warming to his task of denunciation and explanation.

“You know, Yag, when they realized something was up down south in the scrubland—and it didn’t take them long to clock it was a massive Torque-rift—there was a lot of crap talked about what to call it, and the arguments still haven’t died, half a fucking millennium on. Someone named it the Cacotopic Stain, and the moniker stuck. I remember being told in college that it was a terrible populist description, because Cacotopos—Bad Place, basically—was moralizing, that the Torque was neither good nor bad, so on. Thing is . . . obviously, that’s right at one level, right? Torque’s not evil . . . it’s mindless, it’s motiveless. That’s what I reckon anyway—others disagree.

“But even if that’s true, seems to me that western Ragamoll is precisely a Cacotopos. That’s a vast stretch of land which is totally beyond our power. There’s no thaumaturgy we can learn, no techniques to perfect, which’ll let us do anything with that place. We’ve just got to stay the fuck out and hope it eventually ebbs away. It’s a huge fucking badland crawling with Inchmen—which admittedly live outside Torque-zones, as well, but seem particularly happy there—and other things I wouldn’t even bother trying to describe. So you’ve got a force that makes a total mockery of our sentience. That’s ’bad’ as far as I’m concerned. It could be the fucking definition of the word. See, Yag . . . it pains me to say this, it really does, I mean I’m a fucking rationalist . . . but the Torque is unknowable.”

With a huge gush of relief, Isaac saw that Yagharek was nodding. Isaac nodded too, fervently.

“Partly selfish, all this, you understand,” Isaac said, with sudden grim humour. “I mean, I don’t want to be arsing around with experiments and end up turning into some . . . I don’t know, some revolting thing. Just too bloody risky. We’ll stick to crisis, all right? On which topic, I’ve got some stuff to show you.”