Saint Gildas (c. 516 – 570) was a 6th century British priest. He is one of the best-documented figures of the Christian church in the British Isles during the 6th century. His renowned learning and literary style earned him the designation Gildas Sapiens (Gildas the Wise). He was ordained in the Church, and in his works favoured the monastic ideal. Fragments of letters he wrote reveal that he composed a Rule for monastic life that was somewhat less austere than the Rule written by his contemporary, David of Wales, and set suitable penances for its breach. There are two known vitas of Gildas: the earlier written by a monk of Rhuys in Brittany, possibly in the 9th century, the second written by Caradoc of Llancarfan, a friend and contemporary of Geoffrey of Monmouth, composed in the middle of the 12th century.