"The highest is to understand that all fact is really theory. The blue of the sky reveals to us the basic law of color. Search nothing beyond the phenomena, they themselves are the theory." So said Johnann Wolfgang von Goethe, in his Theory of Colours of 1810. He was critical of Isaac Newton's prism-theory (from Opticks of 1704), which he believed to be schematic, underestimating the role of human perception of colour.
The work here, above, below is Colour Square Sphere by Olafur Eliasson. He of the Tate Sun Machine. I'm thinking about Goethe's statement above and his well-known epigram, "The hardest thing to see is what is in front of your eyes".
A function of this project is to see and depict the unseen. That may not necessarily be something at, for example, nano-scale. It may be a thing or event so familiar that it is invisible. That is why Dürer's Turf is so remarkable.
Eliasson's Round Rainbow (2005).