"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.