This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
On Vision and Colours, published by Arthur Schopenhauer in 1816, is often read as a footnote to Goethe's Theory of Colours, written in the older man's shadow at Weimar. The disagreement it records is real and specific. Goethe's Farbenlehre treated color as arising from the interplay of light and darkness as an embodied observer actually perceives it, an argument built from careful description of natural phenomena, rainbows, shadows, prismatic edges, rather than mathematics. Schopenhauer accepted Goethe's central move against Newton, that color belongs to the act of seeing rather than to light itself, but pushed the explanation somewhere Goethe never wanted to go: into physiology. For Schopenhauer color was a specially modified activity of the retina, a claim he tried to make rigorous with a numerical scheme relating the intensity of the retinal response to different hues. Goethe rejected this scheme outright when he read the manuscript, and rejected too Schopenhauer's attempt to redefine the Urphanomen, Goethe's own term for the primal phenomenon of light and dark polarity that grounded his entire method. Where Goethe wanted description that stayed faithful to appearance as experienced, Schopenhauer wanted a cause located in the body producing the experience, a move that anticipates his mature philosophy's insistence that the body is where the thing in itself becomes directly knowable. The two men's break over color theory previews, in miniature, the larger philosophical break to come.