GREGORY THE GREAT 167 went on. Despite his departure Luxeuil remained the center iff monastic life in Gaul. His disciple, St. Gall, had re- mained among the Alamanni, and founded near the Lake of Constance the great monastery which has been named after him, and which has had a Swiss canton named after it, and in whose library many priceless manuscripts have been preserved. Other Irish monks penetrated Germany as far as Salzburg and Wiirzburg. When all the Frankish king- doms were reunited under Dagobert (629-639), St. Aman- Idus went as a missionary to the Basques in the extreme south and to Flanders and Hainault in the extreme north of Gaul. Toward the close of the same century a part of Frisia beyond Flanders and the Rhine was conquered by the Franks, and the Anglo-Saxon missionary Willibrord founded there the episcopal see of Utrecht. The Irish monks had not been sent out by the pope, and, owing to their separate development far away from the in- fluence of oecumenical councils and out of touch The Iris h with the rest of the Christian world, they dif- monasteries « /-»* i_ -e are brought fered in some of their usages from the Church of under papal Rome, especially in their method of determining contro the date of Easter each year. In England these diver- gences led to considerable bitterness between the papal mis- sionaries, who soon spread from Kent to the other king- doms, and the British clergy of Wales and the Irish monks of the north, who in the course of the seventh century visited the South, East, and West Saxons. The chief strong- hold of Irish monasticism continued to be in the Kingdom of Northumbria, and there in 664 the Synod of Whitby finally decided the Easter dispute in favor of the papal party. Thereupon the Irish monks of Lindisfarne with- drew to Iona. From 668 to 690, Theodore of Tarsus, a learned Eastern monk acquainted with Byzantine civiliza- tion, was Archbishop of Canterbury, and thoroughly or- ganized and united the Church in England in accordance with Roman usage. This church union came long before there was a united Anglo-Saxon state. The monaster- ies which the Irish missionaries had founded throughout
