A white dove, which became his emblem, was seen settling on his shoulder.John Davies notes that one can scarcely "conceive of any miracle more superfluous" in that part of Wales than the creation of a new hill. St David's metropolitan status as an archbishopric was later supported by Bernard, Bishop of St David's, Geoffrey of Monmouth and Gerald of Wales.The tradition that he was born at Henfynyw (Vetus-Menevia) in Cardiganshire is not improbable.
Around 550, he attended the Synod of Brefi, where his eloquence in opposing Pelagianism caused his fellow monks to elect him primate of the region.Modern historians are sceptical of some of its claims: one of Rhygyfarch's aims was to establish some independence for the Welsh church, which had refused the Roman rite until the 8th century and now sought a metropolitan status equal to that of Canterbury.(This may apply to the supposed pilgrimage to Jerusalem where he is said to have been anointed as an archbishop by the patriarch).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.As such he presided over the synod of Caerleon (the "Synod of Victory") around 569.
His best-known miracle is said to have taken place when he was preaching in the middle of a large crowd at the Synod of Brefi: the village of Llanddewi Brefi stands on the spot where the ground on which he stood is reputed to have risen up to form a small hill.