Consecutive sentences or verses with the same construction, so that the reader compares what changes from one to the next.
In Crime and Punishment
People are divided somehow into ordinary and extraordinary. The ordinary must live in obedience and have no right to transgress the law, because, you see, they are ordinary. The extraordinary have the right to commit all sorts of crimes and to transgress the law in every way, precisely because they are extraordinary
The two sentences have the same structure, “The ordinary must […]” and “The extraordinary have the right to […].” The symmetry makes visible what changes from one side to the other: the duty of one is the right of the other.