Color is to the eye what birdsong is to the ear: a primal communion between ourselves and nature. The Middle Ages saw further expansion of available colors for artistic and decorative works. A handbook from the 1390s contained recipes for five different pigments of red, six of yellow, seven of green and a variety of blacks and whites. Another medieval writer described pigments with which to dye horses to increase their value. During the 15th century, painters began blending pigments with linseed or other oils, yielding glossier, more multitextured surfaces than their predecessors’ egg-tempera works. European easel painting into the...