'As different as black and white'

'Perhaps the brightest natural material is freshly fallen snow. But it reflects only about 75 percent of the sunlight falling on it. The darkest material that we ordinarily come into contact with'black velvet, say'reflects only a few percent of the light that falls on it. 'As different as black and white' is a conceptual error: Black and white are fundamentally the same thing; the difference is only in the relative amounts of light reflected, not in their color.'

'Carl Sagan, Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium, 1997.