In due time he went to St. Abban, like himself a monk, and the founder of many religious houses. Men called him the "Peacemaker," such was his power over turbulent and violent men. Not long before, he had gone alone and unarmed to meet one of the fiercest barbarians of the land, the heathen chief of a reigning clan, and the terror of the surrounding country. Such was the influence of Abban that the marauder laid down his arms, and became in course of time not only a Christian, but also a monk of exceptionally holy life.

Columba found St. Abban in the Church of one of his religious foundations, known amongst the people as the "Cell of Tears" on account of the contrition of the penitents who frequented it. He besought the holy abbot to pray for the souls of those who through his fault had met their death, and the thought of whose fate had destroyed his peace. He entreated Abban also to pray to God that He would reveal to him through the angel who spoke to him continually of the things of heaven, whether they were saved or lost.

The humility of the holy abbot would not allow him for a long time to accede to this last request; but in the end, so moved was he by the anguish of Columba, that he fell on his knees and implored of God to give this comfort to a soul in pain. The knowledge that he asked was given him; he returned with great joy to his visitor to tell him that, through the infinite mercy of God, the souls of all who had fallen on that fatal day had been saved. The chief solicitude of Columba was now at rest, but the future was not yet clear before him. How was he to mould his life that the days to come might be an atonement for the fault that was past? He had learnt his own weakness, he must lean more than ever on the Strength that cannot fail, and the desire for a more perfect expiation was strong in his heart. He determined to seek out St. Molaise, his "soul's friend," in the lonely isle of Inishmurry and to ask his counsel.

St. Molaise knew well the character of his penitent. The penance that would satisfy that great heart must be full and complete. To Columba the love of country came next to the love of God; the decision was taken ere the penitent had ceased to speak.

It had been decreed, said he, by the Synod that Columba was to win to the faith of Christ as many men as had perished at the battle of Cuil-dreimhne. Let him do so; but that the atonement might be more perfect let him go forth from his own people and his own land, and never look upon the hills of Erin again.

Columba bowed his head before the sentence. "It shall be done," he answered, and none but God was to know what the doing cost him. It only remained to break the news to his friends and kinsfolk. A wail of sorrow rang through Tir-Connell at the tidings.

It is not surprising that the land of Alba over the sea suggested itself at once to Columba as the place of his exile. The little kingdom of Dalriada on the Argyllshire coast was ruled by one of his own kinsmen, and reports of the condition of the surrounding country had possibly reached his ears. The Christianity introduced by St. Ninian two hundred years before had almost disappeared. The ruling chiefs were completely under the influence of the Druids, and heathenism and idolatry were supreme throughout the land. There his apostolic spirit would be able to find ample scope. We are told by some of the old writers that the thought of a missionary journey to Caledonia had been for years one of his dearest projects. If that were so, the time had now come to put it into execution.

Columba chose the companions who were to share in his great undertaking from amongst the monks of Derry. Two cousins of his own, Baithen, who was to succeed him in after years as abbot of Iona, and his brother Cobthach, were amongst the number. But the disciple who loved him the most was Mochonna, son of the King of Ulster, whom Columba considered too young for an enterprise that involved so many dangers, and to whose entreaties he refused to yield. It was not fitting, said he, that the young monk should leave the country of his birth and the parents to whom he was so dear; but Mochonna would not be gainsaid.

"Thou," he cried, "art the father of my soul, and Holy Church is my mother, and my country is the spot where I can work most fruitfully for Christ."

Then, that it might be impossible for his beloved master to leave him behind, he made a vow before all who were present to quit his native land and to follow Columba to the death. It was in this wise that the determined and devoted Mochonna overcame all opposition and obtained his heart's desire. He was to become one of the most active and zealous of the little band of missionaries, in Alba, where he was venerated for many centuries under the name of St. Machor, as the patron and founder of the See of Aberdeen.