According to an article by Donald Parry, the writers of ancient scripture often contrasted one idea in one line or stanza with an opposite or anti-thetical idea in a parallel line or stanza. Proverbs 13:9 records an example of antithetical parallelism:
The light of the righteous rejoiceth:
but the lamp of the wicked shall be put out.
Notice that the contrasted elements (righteous/wicked) are not simple contradictions but opposite aspects of the same idea. The Book of Mormon contains many fine examples of antithetical parallelisms. Alma, in his great discourse to the saints of Zarahemla, utilized this poetic form:
Whatsoever is good
cometh from God,
and whatsoever is evil
cometh from the devil.
[Donald W. Parry, "Antithetical Parallelism in the Book of Mormon," in Reexploring the Book of Mormon, F.A.R.M.S., p. 167] [See the commentary on Alma 5:9]