The step was sandstone, set into the entrance of a building older than the city’s records. Three centuries of feet had worn it concave — a smooth bowl in the center, two ridges at the edges where only rain had touched.
Margaret was hired to replace it. The stone had thinned to less than an inch at its deepest point. Another decade and someone’s heel would go through. She measured the concavity: forty-three millimeters at center. Drew a cross-section. Took rubbings. Cut a new block from the same quarry — they were still operating, which surprised her, though she couldn’t say why a quarry outlasting a step should be surprising in either direction.
She set the flat stone and mortared it in on a Tuesday. By Friday the building manager called.
“People are tripping.”
She came and watched. He was right. Not dramatic falls — small catches, a hitch in the stride at the threshold. Every person’s foot reached for a dip that wasn’t there. Their ankles were calibrated to a concavity that had been removed. The muscle memory of a building’s users, she realized, includes the wear pattern of its surfaces. The step wasn’t just a step. It was an expectation, carried in the tendon.
She pulled the stone.
The question was what to carve. She had the rubbings, the measurements. She could reproduce the original concavity precisely — forty-three millimeters, same radius of curvature, same asymmetry where generations of right-footed leads had worn the left side deeper than the right.
But that felt wrong too. The original concavity had been earned. Three hundred years of leather and rubber and bare feet, rain and frost and the specific grit of that city’s streets tracked in on those specific soles. Carving an imitation of that wear into fresh stone was — she struggled with the word. Not forgery exactly. Closer to taxidermy.
She carved a concavity anyway. Not the original one. Shallower — twenty millimeters. Symmetric, because she couldn’t bring herself to fake the handedness. A suggestion of wear rather than a reproduction of it. Enough dip that the foot wouldn’t catch. Not enough to pretend.
She set the stone. Nobody tripped. The building manager didn’t call.
She went back a year later, not for work. Just to look.
The new stone was already wearing. She could see it — barely, but she could see it, because she knew where to look and how to hold the light. The real wear was forming inside the carved wear. A concavity inside a concavity. Two depressions occupying the same stone, one deliberate and one genuine, layering.
The deliberate one was symmetric. The real one wasn’t. Already, fourteen months in, the left side was wearing faster. The right-footed leads. The same handedness that had shaped the original stone was shaping this one, finding the carved channel and deepening it unevenly, the way a river finds an irrigation ditch and makes it into something the engineer didn’t draw.
She knelt and ran her finger across the surface. Under her fingertip she could feel both curves — the smooth, even one she’d cut, and the faint rougher one forming on top of it, slightly offset, slightly deeper on one side. Two records in the same stone. The carved one would persist underneath as the real one deepened around it. In fifty years a mason with good hands might feel the difference: a layer where the grain was cut, not worn. A stratum. The stone would carry both — what she’d guessed and what had actually happened — and the gap between them would be the most honest thing in the step.
The original stone had been one story: wear. This one would be two: the guess, and the correction.
She stood up and watched a woman walk through the door without breaking stride. The foot found the dip and the ankle accepted it and the woman was inside before the step had finished being stepped on. The whole exchange took less than a second. Three hundred years of information, compressed into a tendon’s expectation, transmitted through twenty millimeters of carved sandstone that was already becoming something she hadn’t carved.
She left it. There was nothing to fix. The stone was doing what stone does when you give it something to be cut through.