[citation needed] Brahms himself believed that the open tones of the natural horn had a fuller quality than those produced by valves.
Brahms also learned natural horn (as well as piano and cello) as a child, which may be another reason why he chose to write for these instruments following the death of his mother.
The contrasting trio section uses transposed material from a small unpublished piano piece (Albumblatt) which Brahms had written twelve years earlier, in 1853.
[2] 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.
In 2006 hornist Radek Baborák took part in the premiere of Miloš Bok's arrangement of the work as a concerto for horn (or viola, or cello), violin and orchestra.