Kentigern — also called Mungo, his affectionate nickname meaning 'dear one' — was a sixth-century British missionary bishop who established Christianity in the kingdom of Strathclyde and became the patron saint of Glasgow. His story comes to us almost entirely through Jocelin of Furness's twelfth-century hagiography, which blends historical memory with legend so thoroughly that separating the two is nearly impossible. What is certain is that Kentigern was remembered as the founding figure of Christianity in the Glasgow region, and that his cult was sufficiently established by the twelfth century to support a major cathedral and pilgrimage tradition.

Kentigern became the subject of extensive hagiographic tradition, particularly in Jocelin's Life. He is presented as man of monastic virtues, miracle-worker, and bishop of spiritual authority. Jocelin records numerous miracles: divine assistance in building Glasgow monastery, healings, exorcisms, miraculous rescues, spiritual visions.

According to Jocelin's Life, Kentigern was the son of a British princess named Teneu (or Thaney), who was seduced or assaulted and cast out by her father. The child was raised by St. Serf at Culross in Fife, who gave him the pet name Mungo. Kentigern was trained in the monastic life and eventually sent to evangelize the Britons of Strathclyde.

He established his base at Glasgow — the name traditionally derived from 'dear green place' — where he founded a monastic community and served as bishop. His ministry was characterized by ascetic discipline, preaching, and the establishment of churches across a wide territory. Political instability in Strathclyde eventually forced him into exile. According to tradition, he traveled to Wales, where he may have met St. David and founded a monastery at Llanelwy (later St. Asaph). He returned to Strathclyde when political conditions changed and continued his episcopate until his death, traditionally dated to January 13, 603.

The historical core is thin but not empty: Kentigern was a real bishop associated with Glasgow and Strathclyde in the sixth century, and his memory was strong enough to anchor a major medieval cult. The Glasgow coat of arms incorporates symbols from his legends.

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