When Brigit came of an age to choose her way of life, she resolved to be a nun, to which her parents made no objection. After due preparation she went to a holy bishop of the neighbourhood, who, at her request, received her, and placed a white robe on her shoulders and a white veil over her head. Here she remained for some time in companionship with eight other maidens who had been received with her, and who placed themselves under her guidance. As time went on, she became so beloved for her piety and sweetness of disposition, that many young women asked to be admitted; so that though she by no means desired that people should be speaking in her praise, the fame of her little community began to spread through the country.
This first establishment was conducted strictly under a set of Rules drawn up by Brigit herself: and now, bishops in various parts of Ireland began to apply to her to establish convents in their several districts under the same rules. She was glad of this, and she did what she could to meet their wishes. She visited Longford, Tipperary, Limerick, South Leinster, and Roscommon, one after another; and in all these places she founded convents.
At last the people of her own province of Leinster, considering that they had the best right to her services, sent a number of leading persons to request that she would fix her permanent residence among them. She was probably pleased to go back to live in the place where she had spent her childhood; and she returned to Leinster, where she was welcomed with great joy. The Leinster people gave her a piece of land chosen by herself, on the edge of a beautiful level grassy plain, well known as the Curragh of Kildare. Here, on a low ridge over-looking the plain, she built a little church, under the shade of a wide-spreading oak tree, whence it got the name of Kill-dara, the Church of the Oak, or as we now call it, Kildare. This tree continued to flourish long after Brigit's death, and it was regarded with great veneration by the people of the place. A writer of the tenth century--four hundred years after the foundation of the church--tells us that in his time it was a mere branchless, withered trunk; but the people had such reverence for it that no one dared to cut or chip it.