We not only owe three of Mozart’s horn concertos to his friendship with Ignaz Leutgeb; the solo part of this unusual chamber music work was also written especially for him. Instead of having two violins, the accompanying string quartet has two violas, which complement the dark and warm timbre of the horn and lend the work a unique tonal effect.

Echoes of motives from the “Abduction from the Seraglio” allow us to suppose that it was composed around the same time as the Singspiel. As the autog...