So time went on, and Kentigern grew into a tall lad, the comfort and joy of his master. He was almost a man now, and it was time that he should leave the monastery and his sheltered life there, and find his own work in the world.
Not in anger this time did he plan his departure, but with a humble heart, and he prayed to God for guidance. Not only was he the cause of much quarrelling and jealousy among the rest, but, what was even worse, people had begun to praise and flatter him and call him a wonderful boy, and he felt sure that it was time he should go. So he made up his mind to leave the monastery, and early one morning, after his work was done, he started forth.
 It was to the river that Kentigern bent his steps, scarcely knowing which way to turn, but drawn to the place where the shepherds' fire had warmed him as a tiny baby, where the cry of the sea-birds and the moan of the sea had drowned his first feeble wail. Journeying on and on by the side of the winding Forth, he reached at last a place where a bridge spanned the silver river. The water was flowing quietly beneath him as he crossed the bridge, but when he had reached the other side it rose higher and higher in a great spate until the bridge was entirely swamped. Then, as Kentigern stood and watched the furious torrent, he saw his old master on the opposite bank, leaning with one hand upon his staff and with the other beckoning him to return. The aged saint had followed him all the long way from the monastery, and his voice came sounding mournfully across the rushing waters.
"Alas, my son, light of my eyes, staff of my old age, wherefore dost thou leave me?"
"My father," cried Kentigern, "it grieves me sorely, but I must go forth to my work. Thou knowest that as truly as I do."
"Then let me come with thee, my son," cried the old man. "Thou hast been mine since the day when the angels sang of thy birth, and the shepherds placed thee in my arms."
"I know it," said the boy, and he stretched out his arms with a loving gesture towards the old man, "but I must go forth, and my work lies yonder, while thy work lies behind. Fare thee well, and  God guard and keep thee until the time when He shall take thee home."
Saint Servanus knew that the boy was right, and that he must finish his life-work alone, while the strong young lad, the herald of the dawn, should carry the light into the dark places of the land. Sorrowfully, then, he returned to the monastery, and Kentigern journeyed on alone.
For a while Kentigern lived and worked at Camock, but as the years went by, the fame of his holy life and the good deeds which he did reached the ears of the king of that country.
The Church was then in evil plight, for although the people had been taught the true religion in days gone by, they had sadly lapsed, and many had learned to worship idols and believe in strange gods, as did the pagans who had invaded their land.
The King and the clergy, therefore, of the Cambrian region sought to strengthen and fortify the Church, and what better weapon could they find for their purpose than this wonderful young man, whose influence over people was so marvellous and who lived such a pure and blameless life?
But when they came to tell Kentigern that they had decided to make him a bishop, he was amazed and dismayed.
"I am too young," he said.
"Thy ways are staid, and thou hast much learning," they answered.
"It would take me from my prayers and meditations," urged Kentigern.
 "There are other souls to be saved besides thine own," they gravely answered.
Then Kentigern bowed his head, and said sadly, "But I am not worthy"; and they answered, "Because thou thinkest thyself unworthy, we are all the more certain that thou art the one man we seek."
There was more talk after this, and at last Kentigern saw that there was no other way but to accept the post of honour and difficulty. A bishop from Ireland was ready to consecrate him to his high office, and he was made Bishop of Glesgu, a little place on the banks of the Clyde. There a wattled church was built and a fortified monastery, and there, in the midst of a wild country and a still wilder people, Kentigern began his rule. Little by little, houses were built close around the church and monastery until a village was formed. Then the village became a town, and as the years rolled by the town grew into the great city of Glasgow.
But in the days of Saint Kentigern Glesgu meant only "the dear family," for so the saint named the little gathering of God's servants who dwelt together under one rule and had all things in common, seeking only to do God's service.
There was no jealousy or ill-feeling now for Kentigern to fight against, for the brethren all loved their bishop and obeyed him as their master. But it was no life of ease to which he was called, but one of difficulty, hardship, and strenuous work. Early in the morning he rose from his bed, which boasted no soft pillow nor warm covering, and however cold the morning, he plunged into the river  close by to brace his body for his day's work. The clothes he wore were rough and coarse below, but above he wore a pure white alb or cloak and the stole of his office over his shoulder. And well might the white folds of his mantle be to men a sign of the pure childlike soul that dwelt in the strong man's body.
It is said that, as he knelt before the altar, the prayers which rose from "the golden censer of his heart" seemed to reach to the very gates of heaven, for often as the faithful people knelt around him they saw a white dove with a golden beak descend and hover above his head, overshadowing with its snowy wings the altar and the kneeling bishop.
There was little rest for the servants of God in those days. Far and near they journeyed among the people scattered around the wild countryside. However far the journey, Kentigern always went on foot, and there was no hardship which he shrank from enduring if he could but bring one lost sheep back into the fold. Preaching, teaching, building churches, strengthening and leading back those that had wandered from the True Light, his work went on from day to day.
But once in the year, when the season of Lent came round, Kentigern left his brethren and went to dwell alone in a far-off cave. It was the time when our Lord had gone into the wilderness to wrestle with the tempter, and well did Kentigern know how blessed it was to be alone with God.
In the lonely cave there was nothing to chain his  thoughts to earth and men. The song of the birds, the rippling laughter of the burns unlocked from their winter bonds of ice, the little grey furry caps of the willow buds, the soft green of the sprouting grass, everything fitted in with the praise and prayer which filled his days.
Then when Good Friday came he returned to his brethren, wan and wasted indeed with fasting, but with a face that seemed to reflect the light of heaven, so near to its gates had he dwelt.
But although Kentigern fasted and endured many hardships, he had always a happy cheerful face, and he had no belief in gloomy looks. Often he would tell his brethren that what he disliked above all was a hypocrite who went about sighing with eyes cast down and a long face. They seemed, he said, to think they were walking after the manner of turtle-doves, whereas in reality it was the peacock they resembled. And what was the use of looking down on the dust when eyes might be lifted to heaven? No, hypocrisy was one of the little foxes that spoiled the grapes, and God loved those who did their work with a cheerful countenance and simplicity of heart.
So many years passed away and then evil times befell the "dear family" at Glesgu. Another king now reigned, one who hated the Church and talked with scornful contempt of the bishop and his workers. The seasons, too, had been bad and the harvest poor, and Kentigern found that there was no corn to feed the brethren nor to give to the poor who came to him for aid.
 It was surely the duty of the King to help his people, so the bishop went boldly to the court and asked that out of his abundance the King would spare corn for his hungry people.
The King laughed aloud at the request and answered with mocking words.
"Thou who teachest others to cast their burden upon the Lord, should surely practise thyself the same. How is it that thou who fearest God art poor and hungry, while I, who have never sought the kingdom of heaven, have all things I can desire, and Plenty smileth upon me? Therefore what thou preachest is a lie."
Calmly then did Kentigern make answer that God has often seen fit to afflict the just and allow the wicked to flourish like a green bay tree.
This enraged the King still further, and he bade Kentigern work a miracle if he could.
"If, without the aid of human hands and trusting only in thy God, thou canst transfer to thy house all the grain that is in my barns, I will yield it to thee as a gift," he said, with a mocking laugh.
Kentigern left the King, carrying with him an anxious heavy heart. There were so many hungry mouths to fill and all depended upon him. But not for a moment did he lose his faith in the goodness of God, and he prayed earnestly to Him that the daily bread might be provided.
That very night a great storm came sweeping down the river and the waters began to rise. Higher and higher swelled the torrent until it overflowed the river bank, and swirling round the  King's barns, it lifted them bodily from the ground and carried them out on to the river. There the current caught them and swept them along till they reached the place where Kentigern dwelt, where it left them high and dry, with not so much as a grain of corn spoilt by the water. So God took the King's gift to feed His people.
The mocking King was filled with fury when he learned what had happened, and so cruel became his persecution of Kentigern and his brethren, that they at last determined to leave the monastery and to seek afar off some place where they might dwell in peace.
Travelling southward, Kentigern dwelt some time in Cumberland, where, as was his custom wherever he rested, he erected a stone cross, as a sign of his faith, at a little place still known as Crossfell. Then, travelling on by the seashore, he sought in the wild country for some convenient place where he might found another home.
There is a legend that tells of a white boar that guided him, but it was more likely a kindly stream like his own river Clyde which led him by its silver thread to a place which seemed all that he could wish.
They were no mere dreamers these monks of old, and they did not look for miracles to work for them when the work could be done with their own hands. The wilderness was soon humming as with a hive of bees, and in a wonderfully short space of time trees were cut down, fashioned into beams, fitted together, and a great wooden church and monastery was built to the glory of God.
 But it seemed as if Kentigern was never to be free from persecution, for scarcely was the monastery finished when the prince of North Britain came riding through the forest with his followers, and demanded what these strangers meant by settling on his land.
In vain did Kentigern answer peaceably. The prince would not be appeased, and in his anger he threatened to pull down the church and chase the builders off the land.
Then a strange thing happened, for suddenly the light of day faded from the eyes of the angry man and black darkness came swiftly over him.
"What is this?" he cried, staggering forward, stretching out helpless groping hands. "The light is gone. I can see nothing."
In haste his men came crowding round and lifted him up, but they saw at once that he was blind and they knew not what to do.
"Bring him hither to me," said Kentigern, and the men led him forward, guiding his stumbling steps.
The heart of the good bishop was touched by the sight of the helpless man, and he earnestly prayed to God that He would lighten the darkness and restore sight to those dull eyes. Even as he prayed the light returned, and the grateful prince knelt at the feet of the saint and kissed the hem of his robe in reverence and thankfulness.
There was no more talk of pulling down the church or chasing the brethren, but the prince humbly sat at Kentigern's feet to be taught to  know the True Light which alone could lighten the darkness of his mind.
So things prospered greatly at the new monastery, which grew even greater and more powerful than the old home at Glesgu. But just as Kentigern was beginning to dream of a rest in his old age and thought to end his days in his peaceful new home, he was called once again to fresh labours.
A new king had come to reign over the Cambrian kingdom; one who loved the Church, and strove to establish it once more in his kingdom. Surely, then, the first thing to be done was to send for the good bishop and bid the shepherd return to gather together his flock once more in the old home at Glesgu.
It was hard to leave the home he had made and begin all over again the old work and struggle, but Kentigern never hesitated. The new monastery was left under the care of a faithful brother, Saint Asaph, and Kentigern once more turned his face northwards and returned to his native land.
Many years he laboured, and with him returned peace and prosperity, for the brethren were busy skilled workers, and they taught the people to work the land to the best advantage. The King, too, put all things in his kingdom under the rule of the wise bishop, so that his word was law throughout the country. And it is said that the holy Saint Columba journeyed from his island home to greet the saint whose fame had spread even as far as Iona.
So the herald of the dawn did indeed bring  light into the dark places of his beloved land, and when his work was done on the morn of the Epiphany, when the silver lamp of the morning star was paling in the light of the coming dawn, the angels came to carry home the soul of him at whose birth they had sung their "Gloria in Excelsis." And surely now their song must have risen in still higher triumph, for his warfare was accomplished, the work of the weary old man was finished, and behold, his soul was still as the soul of a little child!