George Gershwin's Porgy and Bess

Yester-day, I listened to George Gershwin's Porgy and Bess performed by the Bethlehem Orchestra.  I noticed a few things.

In "Clara, Clara, Don't You Be Down-Hearted," I noticed some structural parallelism in the lyrics:  "Clara, Clara, don't you be down-hearted" parallels with "Clara, Clara, don't you be sad and lonesome."  A lot of the Psalms are written this way (with two lines saying almost the same thing but with synonyms), and since there are quite a few religious references in the opera (especially "Oh, doctor Jesus," which not only has religious references but is chanted more than sung, recalling a liturgy and therefore strengthening those connections), I would guess that that parallelism is a conscious echo of that style of writing.

I also noticed some interesting trumpet parts in "Narration (Scene: crap game and murder)."  After the narrator says, "She [Bess] doesn't want to be left alone with the body of Robins when the police arrive," one of the trumpets has a passage that sounds like a police siren.

A few seconds after the trumpet/police siren, there are the first four notes of "Dies Irae."  I think I'm becoming something of a boy-who-cried-wolf with the "Dies Irae," but it does fit the scene.  Furthermore, the narrator's line after those four notes is, "She's desperate," which seems to reflect the mood in the "Dies Irae" too.  Additionally, there's the religious connection with "Dies Irae" and some of the other elements of the opera.