The colours are here arranged in a general way according to the natural order, and the arrangement will be found to be directly applicable in the present case, for the colours diametrically opposed to each other in this diagram are those which reciprocally evoke each other in the eye.
Thus, yellow demands purple; orange, blue; red, green; and vice versa: thus again all intermediate gradations reciprocally evoke each other; the simpler colour demanding the compound, and vice versa.
The cases here under consideration occur oftener than we are aware in ordinary life; indeed, an attentive observer sees these appearances everywhere.
(Johann Wolfgang von Goethe, Zur Farbenlehre/Theory of Colours, 1810 transl. Charles Eastlake. John Murray Publishing: 1840. pp. 20-22)