Sentence: Color, of course, is essential to this, for a display of the passions and emotions on the dark groundwork of the negro skin would be as impossible as a rainbow at midnight, but without the deeply cut and distinctly marked features of the Caucasian, color would be comparatively useless in reflecting the grander emotions of the soul.
Combination: a rainbow at midnight (root: rainbow, modifier: midnight)
Property: impossible
Property type: emergent