Origins and Formation
The Vita Sancti Paterni describes Padarn as Armorican by race, born to his father Petran and mother Guean, both of whom embraced the religious life; his father departed Brittany for Ireland. Scholars have disagreed over his true origins: Thomas Wakeman identified him as a nephew of Hoel of Cornouaille, while Canon G. H. Doble and Emrys George Bowen favoured a Welsh origin, suggesting later confusion with other Breton saints of the same name.
Around 524 Padarn travelled to Ireland to join his father and a company of monks led by his cousin Saint Cadvan who were journeying to Britannia. He studied at Illtud's school, known as Cor Tewdws, before establishing his own monastic foundation.
Llanbadarn Fawr and the Welsh Episcopate
Padarn founded the monastery at Llanbadarn Fawr near Aberystwyth, which became the seat of a new diocese with him as its first bishop. The settlement takes its name from him — 'the great church of Padarn' — and dates from the sixth century, predating the neighbouring town of Aberystwyth; Aberystwyth's castle was itself originally named after Llanbadarn, indicating the settlement's early prominence.
The mother church he founded is commemorated in Saint Padarn's Church, a partly Romanesque parish church on the original site; the present structure dates to 1257.
The Vita relates that Padarn travelled to Jerusalem together with Saints David and Teilo to be ordained bishops by the patriarch, who is said to have given the three the gift of tongues so that all who heard them understood in their own language. The patriarch gave Padarn a crozier and a finely woven tunic. On their return the three saints amicably divided Britannia into three bishoprics.
Return to Brittany
Late in life Padarn returned to Letavia (Brittany), where the Vita reports that his fame filled the region. He made peace with Bishop Samson at Vannes, built a monastery there, and became the seventh bishop of Armorica alongside six other regional bishops.
He appears to be identical with Saint Paternus of Avranches in Normandy. Three solemnities honoured him in Armorica: the day of unity with six chief saints (the Kalends of November), his date of death, and his episcopal ordination (the twelfth day before the Kalends of July).
Miracles and Traditional Accounts
The Vita recounts a dispute with King Maelgwn Gwynedd, who sought to cheat Padarn of monastic property. Two of Maelgwn's heralds were defeated by a trial by ordeal of boiling water, and the king himself was afflicted with sickness and blindness until he asked forgiveness and bestowed lands on Padarn's community, described as reaching from the mouth of the river Rheidiol upwards to where it meets the head of the river Clarach.
The most celebrated episode concerns King Arthur, who attempted to seize Padarn's tunic. When Arthur returned in rage, the earth is said to have opened and swallowed him up to his chin until he repented and begged forgiveness, thereafter taking Padarn as his continual patron. Padarn's vita is notable as one of only a small number of insular and Breton saints' lives that mention King Arthur independently of Geoffrey of Monmouth's Historia Regum Britanniae.
Dedications
Churches dedicated to Padarn include Saint Padarn's Church at Llanbadarn Fawr, a church in Llanberis in Gwynedd, and three churches in Radnorshire.
Sources and Veneration
OrthodoxWiki carries no dedicated hagiographic article on Padarn of Ceredigion; he appears in its Timeline of Saints (feast April 15) and among the Western Saints before the AD 1054 Schism.
Wikipedia records his feast as April 16, while the database entry commemorates him on April 15.