The ‘ Vita Cadoci ,’ written probably at Brecon priory by a Norman monk Lifris or Lifricus , is the longest and most important in the collection of Latin lives of Welsh saints known as B.M. Cotton MS. Vespasian A. xiv . The author probably knew very little at such a late date of the true facts of Cadog 's life, but he is likely to have inherited much local tradition. Cadog is said to have travelled into Cornwall and Brittany and visited Ireland and Scotland and finally to have been carried away in a miraculous manner to Beneventum in southern Italy .
His ‘Vita’ makes it clear that his great achievement was the establishment of the famous Celtic monastery at Llancarfan (originally Nantcarfan ) in the Vale of Glamorgan . Here he became renowned for his great learning , and for his work as a teacher of saints . Topographical evidence may indicate a more certain record of the provenance of a saint's cult than does the literary evidence now available to us, and the distribution of ancient churches named after S. Cadog shows a marked concentration of their number in south-eastern Wales and in Brittany . Others are found in Cornwall (in the parish of Padstow near the shores of Harlyn Bay ), in Anglesey , and at Cambuslang on the Clyde , above Glasgow .
The areas in which the Cadog churches in south-eastern Wales are most closely congregated are the fringes of the Welsh mountain massif that experienced the full effects of Roman life and culture, as distinct from the military occupation of the upland areas. The Severn Sea was also an important artery of prehistoric trade which flourished anew in the post- Roman centuries. Since the Celtic saints followed these ancient sea-routes it is precisely in such an area as south-eastern Wales that we would expect to find the cultural contacts out of which Welsh monasticism arose. This area would seem, therefore, to provide a fitting background to the story of S. Cadog and his many churches in this region form one of several reasons for considering him among the pioneers of Celtic Christianity in Wales . It is significant, also, that many of the ancient churches that still bear his name are found either along the Roman roads or near to a Roman villa or fortification. Churches named after later Celtic saints are seldom located in this manner. S. Cadog 's churches in south-west Wales , in Anglesey , and in Strathclyde indicate that he, in common with so many of the saints , used once more the prehistoric sea-routes that clung to the western seaboard of Britain . While he would appear to have made contact with the north, his main missionary work overseas seems to have been in Brittany . Here his cult emanated from his reputed settlement on the island of Saint-Cado in the Sea of Etel in the Morbihan . He is well represented in church dedications and in the ancient liturgies of Brittany .
Professor Emrys George Bowen, M.A., F.S.A., (1900-83), Aberystwyth
Published date: 1959