There is no evidence that any early monastic foundation in the Celtic world was established in accordance with the Benedictine discipline. Celtic monasticism was quite definitely _sui generis_. The mission of St. German in 429 and 447 probably laid the foundations of it in Britain.
It had achieved some of its greatest victories before St. Augustine of Canterbury was born. Paul Aurelian, the Welsh monk, established the monastery-bishopric of Léon in A.D. 530: Sampson, a compatriot, the similar foundation at Dol in A.D. 565: Tutwal of British Dumnonia was abbot before he became abbot-bishop of Tréguier in the same century. In Ireland the monastery of Clonard was founded before the Benedictine order came into existence. St. Patrick was a contemporary of St. German. Celtic Christianity, while it was practically independent of Rome,[49] became intensely monastic. There is nothing therefore to lead us to regard the canons of St. Petrock, St. Piran, St. Stephen, St. Keverne and St. Probus, mentioned in Domesday Book, as subject to the discipline of St. Benedict. Such evidence as we possess tends to confirm the contrary opinion. What has been said of the order of St. Benedict applies with greater force to that of St. Augustine, the Black Canons, whose earliest foundation in England dates from A.D. 1108, that is, 22 years after Domesday Book was compiled. Cardinal Gasquet truly says the clergy of every large church, as being subject to rule, were called canons. The rule of St. Augustine was not introduced at Bodmin until the time of Bishop William Warelwast (1107-36).[50]
Under the strong pressure exerted by monastic expansion the governmental character of episcopacy became attenuated. This was especially the case in Ireland and in those churches which owed their foundation to Irish missions. The multiplication of bishops tended to degrade the office. It is impossible to read the accounts of monastic rule as developed by St. Bridget at Kildare and by the Irish mission at Iona, and of the mechanical and subsidiary part which the bishops were called upon to play in the drama, without being aware of the subversion of one of the fundamental marks of episcopacy. The present writer has found but slight evidence of this disastrous policy in Wales and Brittany. There the abbot-bishop is seen as the ruler of a monastery or of a tribe. Innumerable monasteries had no bishop at all. The presence of a bishop gave to the monastery the elements of permanence and priority. The Breton and Welsh monastery-bishoprics have in many instances survived as bishoprics up to the present time solely, as it would seem, owing to their early episcopal character.