This sheet music was written in March 1, 1813 and published for the first time in 1888. It is not a part of something. It was written for an unaccompanied choir and is difficult to perform. Voices go from pianissimo to fortissimo with necessary accents. This Kyrie is one of the most beautiful Schubert’s unaccompanied choral songs. The major part of choirs can perform it.