sentences:  The contrasting "trio" section uses transposed material from a small unpublished piano piece ("Albumblatt") which Brahms had written twelve years earlier, in 1853.The Adagio mesto opens with four measures of solo piano in the low register of the instrument; this sets up the solemn, contemplative mood of the movement that is emphasized by the entrance of the violin and horn.Daniel Gregory Mason held the Adagio from the Horn Trio to be one of Brahms's most impassioned and heartfelt slow movements.