"They [the slaves] were dying slowly—it was very clear. They were not enemies, they were not criminals, they were nothing earthly now, - nothing but black shadows of disease and starvation, lying confusedly in the greenish gloom. Brought from all the recesses of the coast in all the legality of time contracts, lost in uncongenial surroundings, fed on unfamiliar food, they sickened, became inefficient, and were then allowed to crawl away and rest. These moribund shapes were free as air—and nearly as thin. I began to distinguish the gleam of eyes under the trees. Then, glancing down, I saw a face near my hand. The black bones reclined at full length with one shoulder against the tree, and slowly the eyelids rose and the sunken eyes looked up at me, enormous and vacant, a kind of blind, white flicker in the depths of the orbs, which died out slowly." (1.40)

The white colonists snatch Africans from their homes, take them to alien places, feed them unfamiliar food, and then work them to death. Nice. Here, white doesn't represent purity or truth, but the last gasp of miserable life before succumbing to death.