Placing opposite ideas or words side by side, so that one illuminates the other by contrast.
In The Master and Margarita
what would your goodness do if evil did not exist, what would the earth be like if its shadows vanished
"Goodness" and "evil" appear side by side, and the "shadows" contrast with what is lit, so that each term is understood only through the other. The opposition sums up Woland's function in the novel.
Part Two, Chapter 29: The fate of the Master and Margarita is decided, Woland