On the Jesuits’ America website, William Van Ornum offers some brief, interesting reflections on how the combination of sound and sense in the Psalms enables them to express “our inchoate longings, or as St. Paul would say, groanings.” The key to this Hebrew form is parallelism:

While parallelism may not be as pleasing to our contemporary ears as rhyming (and this may be because of our own historical conditioning — who knows what calming and hedonic effect it had upon ancient listeners?), it served a very practical purpose in Old Testament times: since the Psalms were presented orally, the repetition of themes in a slightly different way helped create a meld of what was being expressed. The second line is often an intensification of the first, as in the beginning of the Divine Office: “O God, come to my assistance. Lord, make haste to help me.”

Van Ornum, who has a Ph.D. in clinical psychology, goes on to say that this form may have deep roots in the human soul:

Perhaps the Creator has embedded the receptacles for parallel structure in our neural networks. Noam Chomsky (Syntactic Structures, 1957), a psycholinguist who studies the structure and function of language, suggests that the understanding of parallel structure resides within the brain itself. Chomsky’s interest in studying language evolved from reading his father’s book, David Kimhi’s Hebrew Grammar (1952). It is intriguing to discover a meld between ancient Hebrew poetry and modern cognitive science, a confluence made possible by Wisdom herself.