Mercy was not the first to tell you that Cristabel Oct was a delight. When you mentioned her cavalier’s name, she went rigid, as though stung. The Saint of Joy turned to you, scrunch-mouthed and nauseous with rage, and wheezed: “Don’t you ever—ever—use her name with me, you useless child, you impertinent cell,” which was a discovery in and of itself.

Yet it was Augustine who said fervently, “A total delight. Effervescent. Kind to animals and children. A master of the sword. Did not have the intellect you’d ordinarily find in a sandwich or an orange, and was a sickening twerp into the bargain. The Eighth House will never see her like again.”

Anatomist.

What else to call Mercy’s power? As a Lyctor, you could read a human body’s thanergy and thalergy like a book—but a picture book with helpful arrows pointing at places of interest, laying them naked and open to you. If you looked at Ianthe, however, you saw nothing. When you even looked at the nothing, it hurt the eye and wobbled the fat of the brain. Of course, she was no more immune to theorems than you were, but without the clarity of Lyctoral sight those theorems became much harder to use. You could press your hand to Ianthe’s chest, if you wanted—which you didn’t, naturally—and the blood-warm sternum beneath would gradually unfold for you. But it would take effort, and close contact, and you would need to know the sternum.

Mercymorn the First knew the sternum. Mercymorn the First knew the pericardial fat, the soft-tissue secrets of the mediastinum, the false-heart shape of the thymus. You might have to press your whole palm to Ianthe’s breastbone—doubtless—and take valuable seconds to search out the bone, and the things behind the bone, their characters, their locations. Mercymorn could pinpoint your pineal gland with the merest touch to the skull. This was not due to some Lyctoral power that she alone possessed, no honed necromantic theorem; as God had told you, she had simply memorised the body, by rote, over the course of ten thousand years. She had studied the measurements and their range of differences, and on the rare occasions when she needed to assume where something was or how it worked, her assumptions had the accuracy of ten thousand years’ experience. What Mercy didn’t know about the body wasn’t just not worth knowing, said the Emperor; if she didn’t know it, it hadn’t existed previously.

Over the dinner table you asked Augustine why, if it was simply a matter of memory, he hadn’t done the same thing. Ianthe choked discreetly on a forkful of boiled flour-paste shapes in red sauce.

“Lord! I can barely remember what I had for lunch last week,” he said. “Besides, anatomy has too narrow an application.”