Theory of Colours
Goethe recorded the sequence of colours projected at various distances from a prism for both cases (see Plate IV, "Theory of Colours"). In both cases, he found that the yellow and blue edges remain closest to the side which is light, and red and violet edges remain closest to the side which is dark. At a certain distance, these edges overlap—and we obtain Newton's spectrum. When these edges overlap in a light spectrum, green results; when they overlap in a dark spectrum, magenta results.