“O Lux-Prosa: Flavit Auster” (“Flavit Auster” is Latin for “the south wind blew”) is taken from the early 14th century manuscript, the Codex Las Huelgas, which comes from the Cistercian convent of Santa María la Real de Las Huelgas in Burgos, Spain. According to the Wikipedia article:
The manuscript was intended for use in performance, and raises questions regarding performance practice of the pieces it contains, especially the polyphonic repertory. The monastery had a choir of 100 women at one point in the 13th century, and it is believed that this choir of women performed the polyphonic works in the manuscript, despite the Cistercian rules against the performance of polyphonic music.
“Flavit Auster” is a responsory related to Mary Magdalen, & as such is a bit of a departure from Advent/Christmas music, but Montserrat Figueras’ part against the background of the supporting choir members is haunting & beautiful, & it seems an interesting piece to include. The recording comes from Figueras’ 2006 Alia Vox release, Lux Feminae 900-1600—highly recommended, as is all of her music.
Image of the convent of Santa María la Real de Las Huelgas links to its source on Wiki Commons. The image is by Lourdes Cardenal, who makes it available under the Creative Commons Attribution-Share Alike 3.0 Unported license.