David (Welsh: Dewi) was the grandson of Ceredig ap Cunedda, an early Christian Welsh king. Trained by St. Paulinus, he founded twelve monasteries across south Wales and a great monastic settlement at Mynyw (Menevia, now St Davids) in the remote southwestern corner of Pembrokeshire.
His rule was extraordinarily austere. The monks ate only bread, herbs, and water (David himself was called 'the Waterman'), worked their own fields without draught animals, practiced silence, and prayed long hours of the Divine Office. His sermons and miracles drew pilgrims from across Britain.
At the Synod of Brefi (c. 545), called to refute the Pelagian heresy, David spoke with such authority that the ground beneath his feet rose into a hill to allow all to hear him; a white dove settled on his shoulder as he preached. He was acclaimed archbishop of Wales by the assembly. His final words to his monks — 'Be cheerful, keep the faith, and do the little things you have heard and seen with me' — are quoted across Wales to this day.