Eadmer

He became a monk in the Benedictine monastery of Christ Church, Canterbury, where he made the acquaintance of Anselm, at that time visiting England as abbot of the Abbey of Bec.

[5] Eadmer must also be credited with influencing the spread of the doctrine of the Immaculate Conception of the Blessed Virgin Mary in the West when he defended popular traditions in his De Conceptione sanctae Mariae.

The idea began to gain currency in England in the opening decades of the 11th Century and had become the subject of liturgical veneration and a feast day (8 or 9 December) at Canterbury, Worcester and Winchester by about 1030.

The feast had been discarded by Lanfranc in his reorganization of the liturgical calendar after the Conquest and Eadmer's advocacy of a sinless Mary was probably motivated as much by the restoration of local Anglo-Saxon devotions at Canterbury as with the wider propagation of the doctrine.

The fact that the doctrine spread throughout England and France throughout the Twelfth Century may have been largely, and ironically, due to the mis-attribution of Eadmer's De Conceptione Sanctae Mariae to Anselm's authorship.