Born at Venice, this learned man became a monk at Mont-St-Michel, but was critical of the supposed simony of the abbot, and left to become a hermit on Tombelaine (Normandy). About 1066 he was invited by Hugh of Cluny to join his community, then at the height of its fame. Sent by Pope Gregory VII to Spain on a liturgical mission in 1073, he remained at Cluny until 1080, when he again left the community to become a hermit, first in the Pyrenees and then near Toulouse, where he preached to the local peasants. His companion as a hermit for some time was Cardinal Hugh of Remiremont, a former papal legate deposed for simony. Recalled to the monastery in 1085, Anastasius died on the way there and was buried at Doydes. Although his shrine was destroyed by Huguenots, his cult persisted. The new Roman Martyrology stresses his Pyrenaean connection. Feast: 16 October.
J. Mabillon, AA.SS. OSB VI (2), 487;AA.SS. Oct. VII (2), 1125–40;B.L.S., x. 111: Bibl. SS., 1. 1057.