The Ascendancy of Celtic Monasticism. St. Patrick said he converted “all of Ireland.” He baptized thousands and he taught them that their destiny was to leave their homeland, as he himself had done, to take the gospel to the regions beyond. A great number of Irish converts became missionaries. These were the fearless, wandering exiles, the peregrini.
The Celtic Mission to Scotland: St. Columba. Columba, the great missionary to the Scots, departed Ireland at the age of 42, “planning to become an exile for Christ.” Columba established a missionary sending base on the island of Iona. From there he set out to convert the Scots and the northern Picts and the northern English kingdoms. By comparison, the Roman Catholic priests in England confined themselves to the region of Kent, where they established churches instead of missionary monasteries. This is a textbook mistake, if your plan is to expand Christianity to peoples beyond your church. Churches do not send missionaries to establish Christian churches in the regions beyond; missionary bands establish churches in the regions beyond. Thus, the Roman priests in Kent established lighthouses, while the Celtic missionaries far to the north set out with flint in their packs, striking the sparks in “the regions beyond” where the people walked in darkness. Read about Lighthouse and Flint here.
The Peregrini. For more than half a millennium a stream of educated and dedicated men poured from the monasteries of Ireland to “go on pilgrimage for Christ” wherever they might feel themselves divinely led. They were not conscripted or appointed by their superiors. They were fond of citing the example of Abraham who obeyed God’s command, “Leave your country and your kindred, and your father’s house and go to a land that I will show you” (Genesis 12:1). This pattern was followed literally. It was typical too that in the circumstances they broke off communication with their home monasteries. They were not directed by or expected to make periodic reports to a home base. The home base for them was only a prized memory. With a strange eagerness they sentenced themselves to perpetual banishment and went forth never to return. They began the new career without specific plans other than the intention to teach a foreign people. They found their way over rough seas and perilous roads and among strange tribes until they came to a spot that seemed by some circumstance divinely indicated as their place of labor. They bore no resemblance to religious tourists, like the celebrated Aetheria (ca 390) nor yet to the monastic hoboes, excoriated by St. Benedict as gyrovagi.”
Upon arriving in a new place, Celtic missionaries sought favorable relations with a prince or local ruler. When they gained favor from “a man of peace” they would stay and preach under his protection. But the missionaries did not fear to rebuke the mighty, even it if cost them the favor of their benefactors.
The impact of the missionary peregrini was strongly felt in Frankish Gaul through the work of Columbanus. From the time a local ruler gave permission for Columbanus and his men to settle in Annegray, crowds of locals came, repenting of their sins, and asking to receive the remedies (medicamenta) of penance. Soon sheer numbers and the need of productive land required the creation of a new center, Luxeuil, eight miles away, where warm springs had attracted many in Roman times. A monastery was founded and rapidly became a community of thousands.
Columbanus and Gall made a journey of several years to establish more monastery sending bases. The great monastery at St. Gall with its magnificent library was one of these. King Agilulf of Lombardy permitted Columbanus to build a monastery at Bobbio on the Trebbia, a southern tributary of the Po.
In recent years scholars have become aware that Celtic monks played a pioneer role as missionaries in Slavic lands. Nearly a century before Methodius and Cyril arrived in Moravia the Irish monks were already Christianizing that kingdom. There is evidence for the continuing presence of an Irish monastic community in Kiev beginning in the late eleventh century.
Irish missionaries converted thousands throughout Europe. They established churches and missionary sending bases wherever they went. “That one small island should have contributed so rich a legacy to a populous continent remains one of the most arresting facts of European history.” “The weight of the Irish influence on the continent,” wrote James Westfall Thompson, “is incalculable. It penetrated the still unchristianized regions of central Europe . . . For three hundreds years the light of Ireland flamed, shedding its rays upon Scotland, England and the Continent, until diminished in the darkness of the Norse invasions.”
Celtic Missionary Enterprises Ebb Away. About the middle of the eighth century the ebb of Celtic missionary expansion became discernible. The early missionary leaders were gone; the next generation of church leaders was more interested in theological study and the liberal arts than in going as exiles to the regions beyond. “In time little remained of the former Irish spontaneity and self-direction in continental lands. Succeeding generations accommodated themselves to the more efficient polity and routines of what we normally think of as church. The abounding energy and apostolic impetuosity of an earlier day were no longer characteristic. In terms of great leadership and bold endeavor we enter on a descending slope.”
 John Thomas McNeill, The Celtic Churches: A History A.D. 200 to 1200 (University of Chicago Press, 1974). 89
 Ibid. 118
 Ibid. 155
 Ibid. 155-6
 Ibid. 156
 Ibid. 157
 Ibid. 159
 Ibid. 163
 Ibid. 174
 Ibid. 221
 Ibid. 192
 Ibid. 175
 Ibid. 177
 Ibid. 192