Also using the format of One, this work began with the idea of two areas and the surrounding space all treated with interference colours. Since the characteristic colour only becomes visible at a specific angle of viewing relative to the angle of illumination, I expected that the viewer would see only a blank piece of paper with a red violet stripe on it. 

To my consternation the areas with the interference colour exhibited a pale complementary colour display. The reason for this I figured out later as a property of the physics of light. I explain it in another article.