My entry for this week's contest is the seventh piece from Johannes Brahms's Eleven Chorale Preludes (for Organ) (Op. 122).
Brahms's Eleven Chorale Preludes are cornerstones of the organ repertoire. "O Gott, du frommer Gott" is one of my favorites of the chorale preludes.
Among other things these chorale preludes demonstrate Brahms's genius for clear, elegant, and beautifully logical contrapuntal textures.