Many years before this, St. Patrick and the missionaries who worked under his guidance, had converted the greatest part of the Irish people to Christianity. But the time was too short and the missionaries too few to instruct the newly-converted people fully in their faith: so that although they were Christians, many of them had only a poor knowledge of the Christian doctrine. In those times there were certain persons in Ireland called Druids, who were the learned men among the pagans of the day, and who taught the people the pagan religion known as Druidism. They hated the Christian faith, and gave St. Patrick and his companions great trouble by trying to persuade the pagan Irish not to become Christians. They continued in the country till the time of St. Columkille, as active as ever though much fewer; and St. Columkille and the other missionaries of his time had often hard work to win over the people from the false teaching of these druids, and make good Christians of them. A great part of the north of Scotland was then inhabited by a people called the Picts. Those of them who lived south of the Grampian mountains had been converted some time before by St. Ninian of Glastonbury:[143-1] but the northern Picts were still pagans; and Columkille made up his mind to leave Ireland and devote the rest of his life to their conversion. In 563, in the forty-second year of his age, he bade a sorrowful farewell to his native country, and crossing the sea with twelve companions, he settled in the island of Iona, in the Hebrides, which had been presented to him by his relative, the king of that part of Scotland. Here he built his little church and monastery, all of wood, and began to prepare for his glorious work. This little island afterwards became the Greatest religious centre in Scotland: and grand churches and other buildings were erected in and around the site of Columkille's humble structures. For many centuries Iona was held in such honour that most of the kings and chiefs and other great people of Scotland were buried in it; and to this day it is full of venerable and beautiful ruins, which are every year visited by people from all parts of the British Islands. [143-1] Glastonbury, a town in Somersetshire, in England, where in old times there was a celebrated monastery, much reported to by Irish students. The most laborious part of St. Columkille's active life began after his settlement in Iona. He traversed the Highlands of Scotland and the Islands of the Hebrides, sometimes in a rude chariot, sometimes on foot, visiting the kings and chiefs of the Picts, and preaching to them in their homes; and he founded churches and monasteries all over that part of Scotland, just as he had done in Ireland. After many years of incessant labour he succeeded in converting the whole of the northern Picts.