Essentially, I re-learned two things about color that are so intuitive they are extremely easy to overlook.

First, that color is extraordinarily powerful in differentiating details. If you look at the original painting ( The_Loge), you see that the red flowers are mixed in with the stripes of her dress. In the drawing however, it is almost impossible to make out those flowers in the swirling mass of grey-scale tone.

Second, that color has an emotional impact greater than the amount of color used. When I drew her lips, they always seemed too small to me, even though I repeatedly checked them against my reference photo. After verifying for the umpteenth time that they were the right size, I finally understood it was the missing "redness" that made them seem too small! That forever changed how I looked at, and understood, color.

This "colorful" insight left me with a curious irony: the loss of flower detail indicated the importance of accurately drawing the object's form (so it will stand out). And yet, accurately drawing the form of the lips diminished their ability to stand out! But rather than being inhibited by this irony, I choose to use it too my advantage: manipulating form and detail in my drawing to emphasize (or de-emphasize) the effect of color relative to the original image.