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prénoms celtiques et bretons d'Albert Deshayes :
Sous la forme ancienne Columcille, est connu est Bretagne en tant que saint Colomba, dit Colomban d'Iona.
Né en Irlande en 521, il descend de la famille royale des O'Neil. Après avoir dirigé plusieurs monastères en Irlande, dont ceux de Durrow et de Derry, il quitte son pays pour aller évangéliser les Picts, qu'il convertit. Il construit un monastère sur l'île d'Iona, où il meur en 597.
Site en.Wikipedia :
Not to be confused with St Columbanus, also Irish and partly his contemporary.
Saint Columba (7 December 521 – 9 June 597), sometimes referred to as Columba of Iona, or, in Old Irish, as Colm Cille or Columcille (meaning "Dove of the church") was an outstanding figure among the Gaelic missionary monks who, some of his advocates claim, introduced Christianity to the Kingdom of the Picts during the Early Medieval Period. He was one of the Twelve Apostles of Ireland.
Early life in Ireland
Columba was born to Fedlimid and Eithne of the Uí Néill house in Gartan, near Lough Gartan, County Donegal, in Ireland. On his father's side he was great-great-grandson of Niall of the Nine Hostages, an Irish high king of the 5th century.
In early Christian Ireland the druidic tradition collapsed, with the spread of the new Christian faith. The study of Latin learning and Christian theology in monasteries flourished. Columba became a pupil at the monastic school at Clonard Abbey, situated on the River Boyne in modern County Meath. During the sixth century, some of the most significant names in the history of Irish christianity studied at the Clonard monastery. It is said that the average number of scholars under instruction at Clonard was 3,000. Twelve students who studied under St. Finian became known as the Twelve Apostles of Ireland, Columba was one of these. He became a monk and was ordained as a priest.
Tradition asserts that, sometime around 560, he became involved in a quarrel with Saint Finnian of Moville over a psalter. Columba copied the manuscript at the scriptorium under Saint Finnian, intending to keep the copy. Saint Finnian disputed his right to keep the copy. The dispute eventually led to the pitched Battle of Cúl Dreimhne in 561, during which many men were killed. Columba's copy of the psalter has been traditionally associated with the Cathach of St. Columba. A synod of clerics and scholars threatened to excommunicate him for these deaths, but St. Brendan of Birr spoke on his behalf with the result that he was allowed to go into exile instead. Columba suggested that he would work as a missionary in Scotland to help convert as many people as had been killed in the battle. He exiled himself from Ireland, to return only once again, several years later.
In 563 he travelled to Scotland with twelve companions, where according to his legend he first landed at the southern tip of the Kintyre peninsula, near Southend. However, being still in sight of his native land he moved further north up the west coast of Scotland. In 563 he was granted land on the island of Iona off the west coast of Scotland which became the centre of his evangelising mission to the Picts. However, there is a sense in which he was not leaving his native people, as the Irish Gaels had been colonizing the west coast of Scotland for the previous couple of centuries. Aside from the services he provided guiding the only centre of literacy in the region, his reputation as a holy man led to his role as a diplomat among the tribes; there are also many stories of miracles which he performed during his work to convert the Picts. He visited the pagan king Bridei, king of Fortriu, at his base in Inverness, winning the king's respect. He subsequently played a major role in the politics of the country. He was also very energetic in his evangelical work, and, in addition to founding several churches in the Hebrides, he worked to turn his monastery at Iona into a school for missionaries. He was a renowned man of letters, having written several hymns and being credited with having transcribed 300 books. One of the few, if not the only, times he left Scotland after his arrival was toward the end of his life, when he returned to Ireland to found the monastery at Durrow. He died on Iona and was buried in the abbey he created.
Several islands are named after Columba in Scotland - including "Ì Chaluim Chille" (one of the Scottish Gaelic names of Iona), Inchcolm and Eilean Chaluim Chille
Columba is credited as being a leading figure in the revitalization of monasticism, and "[h]is achievements illustrated the importance of the Celtic church in bringing a revival of Christianity to Western Europe after the fall of the Roman Empire". It is said Clan Robertson are heirs of Columba, the blood line now resides with Ethan and Gregory Robertson. 
The main source of information about Columba's life is the Vita Columbae by Adomnán (also known as Eunan), the ninth Abbot of Iona, who died in 704. Both the Vita Columbae and Bede record Columba's visit to Bridei. Whereas Adomnán just tells us that Columba visited Bridei, Bede relates a later, perhaps Pictish tradition, whereby the saint actually converts the Pictish king. Another early source is a poem in praise of Columba, most probably commissioned by Columba's kinsman, the king of the Ui Neill clan. It was almost certainly written within three or four years of Columba's death and is the earliest vernacular poem in European history. It consists of 25 stanzas of four verses of seven syllables each.
The earliest recorded example of the name Arthur in a British document occurs, as Arturius, in Adomnan's vita. There it occurs as the name of a prince among the Scots, the son of Áedán mac Gabráin, king of Dál Riata from AD 574, far from the legendary King Arthur's familiar haunts in the southwest.
The vita of Columba is also the source of the first known reference to a Loch Ness Monster. According to Adomnan, Columba came across a group of Picts who were burying a "poor little man" who had been killed by the monster, and saved a swimmer with the sign of the Cross and the imprecation "You will go no further", at which the beast fled terrified, to the amazement of the assembled Picts who glorified Columba's God. Whether or not this incident is true, Adomnan's text specifically states that the monster was swimming in the River Ness -- the river flowing from the loch -- rather than in Loch Ness itself.
Through the reputation of its venerable founder and its position as a major European centre of learning, Columba's Iona became a place of pilgrimage. A network of Celtic high crosses marking processional routes developed around his shrine at Iona.
Columba is historically revered as a warrior saint, and was often invoked for victory in battle. His relics were finally removed in 849 and divided between Alba and Ireland. Relics of Columba were carried before Scottish armies in the reliquary made at Iona in the mid-8th century, called the Brecbennoch. Legend has it that the Brecbennoch, was carried to Bannockburn by the vastly outnumbered Scots army and the intercession to the Saint helped them to victory. It is widely thought that the Monymusk Reliquary is this object.
O Columba spes Scotorum... "O Columba, hope of the Scots" begins a 13th century prayer in the Antiphoner of Inchcolm, the "Iona of the East".
St Columba's feast day is June 9 and with Saint Patrick, March 17, and Saint Brigid, February 1, is one of the three patron saints of Ireland. Prior to the battle of Athelstaneford, he was the sole patron saint of Scotland. He is also venerated within the Orthodox faiths as a saint and Righteous Father.