In pigmentation, white is none and black is all. That is why you shouldn't wear black on really hot days. Black absorbs the whole spectrum of light and the light energy ends up converted to heat energy.
In light, white is all colors and black is none. White objects reflect all light. That's why, if you shine a white light through a crystal, the light spectrum is revealed- because it's all there (in the white light). Since black absorbs the light spectrum, it doesn't reflect anything, so we can't see color.