Brahms: Ein deutsches Requiem, Op. 45: I. Selig sind, die da Leid tragen

Last week, I listened to Brahms' Ein deutsches Requiem, Op. 45.  I've listened to it only a handful of times (eight, according to my records), so I'm not that familiar with it, but I did notice a small feature in the first movement (Selig sind, die da Leid tragen).

Here are the first few bars of the string parts:

[source]

The third bar of the cello part and the fifth and seventh bars of the viola (Bratschen) part match the first bar of a tune that Haydn wrote.  Here's the first phrase:

In The Lutheran Service Book, this tune has the title "Austria."

According to Britannica, Haydn's tune was paired with the text of the "Deutschlandlied" in the 1840s, although it didn't become the official national anthem of Germany until 1922.  Brahms' requiem is from the 1860s, a few decades later.  It seems, then, that he took the opening notes of the "Deutschlandlied" and put them here at the beginning of his requiem, as if to indicate its "German-ness."

"Austria"

One of my musical projects this year is to listen to Haydn every Thursday.  Along with pieces in my collection, I've been watching some performances on YouTube.  Last week, I watched this performance of the Quartet in C major, Op. 76, No. 3 "Emperor."  The second movement has the structure of a theme and variations.  According to Encyclopedia Britannica, Haydn wrote the theme by itself and then later incorporated it into the string quartet.  In any case, I discovered that, with some slight adaptions, this theme appears in The Lutheran Service Book as the tune "Austria," used for #648 "Glorious Things of You Are Spoken."  Originally, the tune was used for Austria's national anthem, which is apparently the source of its name, and it's currently the tune for Germany's national anthem.