David was a native of Wales, and a relatively large amount of information is known about his life. He is traditionally believed to be the son of Saint Non and the grandson of Ceredig ap Cunedda, king of Ceredigion.
He became renowned as a teacher and preacher, founding monastic settlements and churches in Wales, Dumnonia, Armorica, and Brittany. St David's Cathedral stands on the site of the monastery he founded in the Glyn Rhosyn valley of Pembrokeshire. Around 550, he attended the Synod of Brefi, where his eloquence in opposing Pelagianism caused his fellow monks to elect him archbishop of the region. As such he presided over the synod of Caerleon (the "Synod of Victory") around 569.
The Monastic Rule of David prescribed that monks had to pull the plough themselves without draught animals, must drink only water and eat only bread with salt and herbs, and spend the evenings in prayer, reading and writing. No personal possessions were allowed: even to say "my book" was considered an offence. He lived a simple life and practised asceticism, teaching his followers to refrain from eating meat and drinking beer.
Though the exact date of his death is not certain, tradition holds that it was on March 1, which is the date now marked as Saint David's Day.
His last words to his followers were in a sermon on the previous Sunday. The Welsh Life of St David gives these as, "Arglwydi, vrodyr, a chwioryd, Bydwch lawen a chedwch ych ffyd a'ch cret, a gwnewch y petheu bychein a glywyssawch ac a welsawch gennyf i. A mynheu a gerdaf y fford yd aeth an tadeu idi", which translates as, "Lords, brothers and sisters, Be joyful, and keep your faith and your creed, and do the little things that you have seen me do and heard about. And as for me, I will walk the path that our fathers have trod before us."
Blessed Dewi, ora pro nobis
