The tracing house is quiet the way a held breath is quiet.

The floor is lime plaster, swept, a pale field for full-size thinking. Compass. Square. Chalk line. A string still pegged where yesterday’s vault-rib was drawn: a pointed pair of arcs meeting like two hands in prayer, which is a pretty way to say this shape carries weight.

Gareth is there, visiting mason, lime in his beard. He learned his trade on round arches, thick walls, windows like polite slits. He taps the nave wall with his knuckle through the open door.

“That old arch doesn’t fall,” he says. “Copy what works. Pointed is fashion. Fashion does not hold a roof.”

Maud, from the threshold: “Fashion that lets the shove go down the pier instead of out the wall is called geometry, Gareth. Use the 3-4-5 and square the bay, or copy the nave and watch the new piers argue.”

Kit sits on a bucket, too ready to run a template to the yard.

The bay of the crossing is a rectangle that must be a rectangle, not a tired parallelogram. A triangle with sides three, four, and five has a right angle. String does not lie unless a person helps.

The tracing house sits south of the choir so rain does not print the drawings and so masons can walk a template to the yard without crossing the nave during office. Full-size is the point: a vault rib is too proud to be guessed in a palm-sized sketch. Gareth is not a fool. Round arches carried the nave through storms you were not alive for. The choir’s piers were set to a different tune. Mixing tunes is how you get a stone that fits a church that is not here.