“ ’Stail, Yag, this is stuff I’ve been working on for years! It’d almost turned into a kind of hobby. But then this morning I looked again at some notes I’d made early on in your case, and I linked it up with all my old ideas, and I saw that this was the way to go. And I’ve been wrestling with it all day.” Isaac shook a piece of paper at Yagharek, a piece of paper on which was a triangle containing a cross.

Isaac grabbed a pencil and wrote words at the three points of the triangle. He turned the diagram to face Yagharek. The top point was labelled Occult/thaumaturgical; the bottom left Material; the bottom right Social/sapiential.

“Righto, now, don’t get too bogged down with this diagram, Yag old son, it’s supposed to be an aid to thought, nothing more. What you’ve got here is a depiction of the three points within which all scholarship, all knowledge, is located.

“Down here, there’s material. That’s the actual physical stuff, atoms and the like. Everything from fundamental femtoscopic particles like elyctrons, up to big fuck-off volcanos. Rocks, elyctromagnetism, chymical reaction . . . All that sort of thing.

“Opposite, that’s social. Sentient creatures, of which there’s no shortage on Bas-Lag, can’t just be studied like stones. By reflecting on the world and on their own reflections, humans and garuda and cactacae and whatnot create a different order of organization, right? So it’s got to be studied in its own terms—but at the same time it’s also obviously linked to the physical stuff that makes everything up. That’s what this nice line is here, connecting the two.

“Up top is occult. Now we’re cooking. Occult: ‘hidden.’ Takes in the various forces and dynamics and the like that aren’t just to do with physical bits and bobs interacting, and aren’t just the thoughts of thinkers. Spirits, dæmons, gods if you want to call them that, thaumaturgy . . . you get the idea. That’s up at that end. But it’s linked to the other two. First off, thaumaturgic techniques, invocation, shamanism and so on, they all affect—and are affected by—the social relations that surround them. And then the physical aspect: hexes and charms are mostly the manipulation of theoretical particles—the ‘enchanted particles’—called thaumaturgons. Now, some scientists—” he thumped his chest “—think they’re essentially the same sort of thing as protons and all the physical particles.

“This . . .” said Isaac slyly, his voice slowing right down, “is where stuff gets really interesting.