[T]he dyeing trades were specialized and compartmentalized according to textile (wool, linen, silk) and color. Regulations forbade working in a range of colors for which one was not licensed. With regard to wool, for example, a dyer of red could not dye it in blue, and vice versa. On the other hand, bue dyers were often responsible for green and black shades, and red dyers for the range of yellows and whites. This strict specialization in the dyeing occupations hardly comes as a surprise to the historian of colors. It must be seen in the context of that aversion to mixtures, inherited from the biblical culture, that deeply permeated medieval sensibility and symbolism. Its repercussions in social life and material culture were numerous. Mixing, blurring, merging, combining were often considered demonic operations because they infringed upon the Creator’s desired order. All those whose professions required them to do so (dyers, smiths, alchemists, apothecaries) prompted fear of suspicion; they seemed to be cheating with matter. Dyers were the primary targets, as is evident from the French play on words, common int he 1500s, that connects the verbs teindre and feindre, “to dye” and “to pretend.” We find it again in English a few decades later (in Shakespeare, for example), where there is a thin line between “to dye” and “to lie.”

Thus dyers in the late Middle Ages rarely mixed two colors to make a third—and especially not blue and yellow to obtain green—not only because of the taboos just noted but also because of professional compartmentalization: since blue vats and yellow vats were not found in the same facility, it was materially impossible to mix those two colors.

green the history of a color, p. 114

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