Repetition / Erosion is a contemporary approach to the Cantigas de Santa Maria, a 13th century Galician song collection, through the lens of Erosion. Cantigas de Santa Maria is one of the largest song collections from the Middle-Ages, with a total of 427 songs. Dedicated to the Virgin Mary, the collection alternates poems narrating stories of miracles and praising Hymns. The overall work, written in vernacular language (Galaico-Portugues) is oscillating between courtly love tellings and liturgy.  Besides its literary and musical legacy, this work can also be read as a chronicle of both cultural and mystical life in Europe during the 13th century and reveals the blurred line between sacred and folklore. The project plays with different scales of time: geological, historical, musical and human. In constant evolution, the performance consist of a succession and/or superposition of repetitive tasks addressing the different aspects of the songbook : musical, poetic, iconographic, historic…