A gallery space is divided by a plastic sheet into two parts, one larger, one smaller. An opening allows visitors to walk from one side to the other. The space is constantly saturated in yellow monofrequency light, in which the blue sheet appears black. Every three and a half minutes, 14 white floodlights fixed to the wall fade in. Lit for 20 seconds, these restore visitors' customary spectral perception of the room. Slowly, the floodlights fade out, re-introducing the yellow and black duotone caused by the monofrequency lights.