The Paraguayan composer and guitarist Agustín Barrios Mangoré spent his last days in San Salvador, Salvador. One evening as he sat in his home, he heard an old, blind beggar woman going from door to door. At each door she came to she gave the same rhythmic knock and begged in the same words : “una limosna por el amor de Dios” – an alm for the love of God.
Barrios was moved to compose a brief piece of music for the solo guitar which stands as one of the most brilliant and haunting tremolo pieces in the repertoire. Barrios’ health was failing as he wrote una limosna and he was aware it would be his last composition. The melody in tremolo covers almost the full range of the instrument and evokes need and longing; love and desperation; resignation and joy. Underlying the melody, the knock of the beggar can be heard - an insistent bass ostinato that repeats for the duration of the piece.
A number of recordings of una limosna are available, including I believe, Barrios' own - one of the first recordings on the newly invented gramophone. The original recordings are of poor quality and almost unlistenable. The guitarist John Williams (not to be confused with the film-score composer) devoted much time to painstakingly transcribing from the originals. His performances of Barrios' compositions, including una limosna, helped trigger a revival of interest in the man and his work and are highly recommended.
An essay on Barrios' life and work : http://www.cybozone.com/fg/jeong.html
Guitar tablature at http://www.classtab.org/abmeutz.txt
Una limosna played by Ioana Gandrabur here. Sound quality limited.