It is now acknowledged on all sides, that, though not the first preachers of Christianity in Scotland,[73] the Irish were at least by far the most active and the most influential of our early missionaries; and truly a new epoch began in Scottish history when, in the year 563, St. Columba, "pro Christo peregrinari volens," embarked, with his twelve companions, and sailing across from Ireland to the west coast of Scotland, founded the monastery of Iona. It is certainly to St. Columba and his numerous disciples and followers that the spread of Christianity in this country, during the succeeding two or three centuries, is principally due. At the same time we must not forget that numerous other Irish saints in these early times engaged in missionary visits to Scotland, and founded churches there, which still bear their names, as (to quote part of the enumeration of Dr. Reeves) St. Finbar, St. Comgall, St. Blaan, St. Brendan, the two St. Fillans, St. Ronan, St. Flannan, St. Beranch, St. Catan, St. Merinus, St. Mernoc, St. Molaise, St. Munna, St. Vigean, etc.[74] Along with their Christian doctrines and teachings these Irish ecclesiastics brought over to Scotland their peculiar religious habits and customs, and, amongst other things, imported into this country their architectural knowledge and practices with regard to sacred and monastic buildings. In the western parts of Scotland, more particularly, numerous ecclesiastical structures were raised similar to those which were peculiar to Ireland; and various material vestiges of these still exist.[75] In the eastern parts of Scotland, to which the personal teaching of the Irish missionaries speedily spread, we have still remaining two undoubted examples of the repetition in this country of Irish ecclesiastical architecture in the well-known Round Towers of Abernethy and Brechin, and perhaps we have a third example in the stone-roofed oratory of Inchcolm.