One of the chief agents in this result was the Irish monk Aidan, who had fixed his seat in the little peninsula of Lindisfarne, and from whose monastery, as from another Iona, missionaries poured over the North of England.  At Lichfield, Whitby, and many other places religious houses sprang up, all owing their allegiance to Lindisfarne, and through it to Iona and Ireland.

In this very fervour there lay the seeds of a new trouble.  A serious schism arose between Western Christendom and the Papacy.  Rome, whether spiritually or temporally, was a name which reverberated with less awe-inspiring sound in the ears of Irishmen (even Irish Churchmen) than, probably, in those of any other people at that time on the globe.  They had never come under the tremendous sway of its material power, and until centuries after this period—­when political and, so to speak, accidental causes drove them into its arms—­its spiritual power remained to them a thing apart, a foreign element to which they gave at most a reluctant half adhesion.

From this it came about that early in the history of the Western Church serious divisions sprang up between it and the other churches, already being fast welded together into a coherent body under the yoke and discipline of Rome.  The points in dispute do not strike us now of any very vital importance.  They were not matters of creed at all, merely of external rule and discipline.  A vehement controversy as to the proper form of the tonsure, another as to the correct day for Easter, raged for more than a century with much heat on either side; those churches which owed their allegiance to Iona clinging to the Irish methods, those who adhered to Rome vindicating its supreme and paramount authority.

At the Synod of Whitby, held in 664, these points of dispute came to a crisis, and were adjudicated upon by Oswin, king of Northumbria; Bishop Colman, Aidan’s successor at Holy Island, maintaining the authority of Columba; Wilfrid, a Saxon priest who had been to Rome, that of St. Peter.  Oswin’s own leaning seems at first to have been towards the former, but when he heard of the great pretensions of the Roman saint he was staggered.  “St. Peter, you say, holds the keys of heaven and hell?” he inquired thoughtfully, “have they also been given then to St. Columba?” It was owned with some reluctance that the Irish saint had been less favoured.  “Then I give my verdict for St. Peter,” said Oswin, “lest when I reach the gate of heaven I find it shut, and the porter refuse to open to me.”  This sounds prudent, but scarcely serious; it seems, however, to have been regarded as serious enough by the Irish monks.  The Synod broke up.  Colman, with his Irish brethren, and a few English ones who threw in their lot with them, forsook Lindisfarne, and sailed away for Ireland.  From that moment the rift between them and their English brethren grew steadily wider, and was never afterwards thoroughly healed.