From Lanigan's An Ecclesiastical History of Ireland (1822, vol. iv, chapt. xxviii, p. 172ff.):
The see of Dublin being now vacant several competitors started for it but the electors fixed their eyes upon the holy abbot of Glendaloch Laurence O'Toole who for a long time resisted their proposal and wishes but at length was forced to submit and was consecrated archbishop in the cathedral of Dublin by Gelasius the primate accompanied by many bishops. (44) This was in the year 1162 (45) The original name of this great and good man was Lorcan (46) and he was of the illustrious house of the O Tuathals being the youngest son of Muriartach O Tuathal prince of Imaly or Imaile in the now county of Wicklow. (47) His mother was of the equally great family of the Hy Brins now usually called Byrne. (48) Lorcan or Laurence remained with his parents until he was about ten years old when he was given as a hostage by his father to the king Diermit. (49) This wicked king bore a great hatred to Muriartach and sent the boy to a barren district where he was treated with great cruelty. His father on being apprized of it seized upon twelve of Diermit's soldiers and threatened to put them to death unless his son was restored to him Diermit alarmed at this menace and knowing that Muriartach's territory was impregnable and could defy all his power thought it adviseable to dismiss Laurence and sent him not to his father but to the bishop of Glendaloch under the condition of getting back his twelve soldiers. The good bishop kept Laurence with himself for 12 days placing him under the care of his chaplain who treated him very kindly and instructed him in the principles of the Christian doctrine Laurence who was at that time 12 years old then returned to his father's residence. (50)
After some days his father taking Laurence with him paid a visit to the bishop of Glendaloch and proposed to him to inquire by casting lots which of his sons he should dedicate to the ecclesiastical state. Laurence on hearing this is reported to have laughed and said Father there is no necessity for casting lots if you allow me I will embrace it with pleasure. The father smiled and the bishop and others present were rejoiced to find that a boy of such high lineage should offer himself for the service of the Church. His father then consenting with joy and taking him by the right hand offered him to God and St. Coemhgen the patron of Glendaloch recommending him to the care of the bishop for his instruction in learning and piety. Under his tuition and protection Laurence made great progress in the religious duties and acquirements necessary for a clergyman but after some years he lost this worthy friend and master who was carried off by death. (51) Yet he still persevered in his pious pursuits and continued to improve in virtue so that after some time he was when 25 years of age elected abbot of the monastery of Glendaloch which was distinct from the bishopric. (52) This abbey was very rich and it had been the custom to choose for its abbots men of the highest families who might be able to protect the adjacent country Laurence made the best possible use of the wealth of the monastery distributing it among crowds of distressed and poor persons who were afflicted by a dreadful famine that raged throughout all that district for four years. (53) He used to provide them by means of his monks with corn and other necessaries and his liberality was so extensive that at length the riches of the abbey not being sufficient for the wants of the poor he distributed among them a treasure which his father had left with him in deposit. He was however as great and holy men usually are reviled by certain false and envious brethren but who with all their malignity could not find any thing in his conduct deserving of reproach. By dint of prayers he cleared the country from some powerful robbers who were overtaken by the divine vengeance. Towards the end of the first four years of his administration tranquillity was restored and a very abundant harvest ensued yet Laurence still continued his largesses to the poor and set about building churches. About this time the then bishop of Glendaloch died and every one called out for Laurence as his successor. But he refused to accept of the appointment excusing himself on his not having as yet reached the age required for a bishop. (54) Some years after these occurrences Gregory archbishop of Dublin died and Laurence was as we have seen appointed his successor. (55)
In the same year 1162 Gelasius of Armagh held a synod at Clane in the now county of Kildare which was attended by 26 bishops many abbots and other clergymen. After enacting several decrees relative to Church discipline and morals it was ordered with the unanimous consent of the synod that for the future no one should be admitted a Fer leghinn that is a professor or teacher of theology in any church in Ireland unless he had previously studied for some time at Armagh. (56) When returned to his diocese Gelasius did not remain idle but immediately made a visitation of it exerting himself most strenuously to correct whatever abuses fell in his way. (57) To said year 1162 is assigned the death of Cathasac, a scholastic of Derry. (58)
Notes in Lanigan
(45) Four Masters ap. Tr. Th. p 309. Ware Archbishops of Dublin at Laurence O Toole
(46) Four Masters ib. Lorcan was latinized into Laurentius. In the quoted Life cap. 2 there is a ridiculous story about his having been called Laurentius from laurus laurel
(47) In said Life cap. 1 his father is called Muriartach O'Toheil and is made king of Leinster. This is a mistake for the O'Tuathal country was far from comprizing all that province. In Butler's Life of St. Laurence at 14 November the principality of Muriertach or Maurice is said to have been in the vicinity of Dublin But Imaile or as usually called the Glen of Imaile is several miles from Dublin lying to the SW of Glendaloch and stretching to near the town of Donard.
(48) The author of the Vit. S.L. says cap. 1 that the saint's mother was called Inian Ivrien that is as he adds daughter of a prince. But this is not the meaning of the words which ought to be translated daughter of Hy Brin or O'Brin from the Irish Ingean pronounced like Inian a daughter and Ivrien that is Hy Brin. It is strange that Harris did not see into this when quoting Archbishops of Dublin at Laurence 8 c. the passage of that author. In a note to the Life in Butler I find instead of Hy Brin or O Brin alias Byrne the name written O Brian. This is wrong for the O Brians were a quite distinct family being of the Dalcassian princes of Munster whereas the O Brins were originally a Leinster house supposed to be descended from the celebrated king Brandubh who was killed about the year 602.
(49) This Diermit is usually and I think justly supposed to have been the famous Dermod Mac Morough king of Leinster although Usher Syllog. Not. ad No. 48 makes him a different person. But I believe he was mistaken Mac Morough was king of Leinster at the time that St. Laurence was ten years old.
(50) Vit. S.L. cap. 3 The then bishop of Glendaloch was apparently the immediate predecessor of Gilla na Naomh Laignech who assisted at the council of Kells but his name is not known.
(51) ib. capp. 4, 5.
(52) In Butler's Life this matter is not stated correctly. In it we read Upon the death of the bishop of Glendaloch who was at the same time abbot of the monastery. Laurence though but 25 years old was chosen abbot and only shunned the episcopal dignity by alleging that the canons require in a bishop thirty years of age. Now in the first place there is no authority for saying that the bishop was also abbot of the monastery. What the Latin Life has is merely that there were in the church of Glendaloch both an episcopal see and an abbey but it does not state that any bishop possessed them both together. On the contrary it constantly represents them as quite distinct and informs us cap. 6 that the abbey was far more wealthy than the see. Nor had Butler any reason for supposing that it was upon the death of the bishop that Laurence was chosen abbot and probably a considerable time elapsed between said death and Laurence's promotion to the abbacy. Next comes a great mistake in Butler's imagining that the bishop after whose death Laurence shunned the episcopal dignity was the same as the one by whom he had been instructed and after whose death he became abbot as if the appointment to the abbacy and the offer of the bishopric had taken place at the same time Laurence was as will be soon seen abbot for four years before he refused to accept of the see that became vacant at the end of them by the death of the bishop who consequently was not the one who had been his master but his successor.
(53) I do not know why Butler has four months instead of four years for in Messingham's edition of the Latin Life four years are mentioned in cap. 6 and cap. 9 54 Vit. S.L. cap. 10 Laurence was then only 29 years old having been appointed abbot at the age of 25. That foul mouthed liar Ledwich gives Antiq. etc. p. 48 as the reason of Laurence not having accepted of the see of Glendaloch that his ambition aspired to an higher dignity the pall and the see of Dublin and he soon attained them. But he did not soon attain them for some years intervened before he became archbishop of Dublin. What idea could he have had at that time of his ever being chosen to govern the Danish city of Dublin he a Tuathal an O'Toole. It is as clear as day light that instead of having an eye to that situation he was forced to submit to it the proposal relative to it having come without his knowledge from the electors of Dublin. The fact is that Laurence did not wish to be a bishop at all. Many a conscientious man may agree to being made abbot but holy men do not aspire to bishoprics Harris was much more honest who says Archbishops of Dublin at Laurence that he could not have the opportunities of exerting his strong disposition to charity when bishop of Glendaloch as he had when abbot because the revenues of the bishopric were infinitely inferior to those of the abbacy. The bishop in whose stead it was proposed to appoint Laurence was I am sure Gilla na Naomh mentioned above Note 50. In what year he died I do not find but it must have been between 1152 and 1161 the year of the death of Gregory of Dublin.
(55) Butler is wrong in stating that St. Laurence was only thirty years of age about the time of Gregory's death. This cannot agree with the Latin life which states cap. 10 that a no short time "non breve tempus" elapsed between the time of Laurence's refusing the see of Glendaloch and that of the death of Gregory. Now Laurence was 29 years old when he made that refusal and in Butler's hypothesis only one year would have passed between it and said death. But surely so short a space would not have been called a "non breve tempus" or how could the author of said Life have said cap. 33 that he died full of days plemts dierum if he was only about thirty when he became archbishop of Dublin. For in this case he would not have outlived the age of fifty whereas his incumbency began in 1162 and he died in 1180. Accordingly Harris was right ib. in reckoning some years between his refusal of the see of Glendaloch and the death of Gregory.
(56) Thus the Life of Gelasius cap. 23 and the 4 Masters ap. Tr. Th. p. 309. But according to certain anonymous annals quoted by Harris (Bishops at Gelasius) the decree was, as he explains it, that they should have been fostered or else adopted by Armagh. As to fostered it means that they must have studied at Armagh conformably to the phrase alumnus which is used for a student in a university or college thus "ex c. alumnus universitatis Parisiens" signifies a student of the university of Paris. But the words adopted by Armagh indicate a class of persons who had not actually studied there but who should be approved of by to use a modern technical term the faculty of Armagh and authorized by it to teach theology publicly in the same manner as in our times degrees and diplomas are taken out at universities and in many of them are granted after previous examination to persons who had studied elsewhere. It is very probable that the decree of Clane did not require that all those who might afterwards be appointed public professors of theology should have actually studied at Armagh and that it was sufficient that on their capability being ascertained they had been approved of by the president and doctors of that distinguished school. It is difficult to think that while there were several other great schools in Ireland "ex c. Lismore Clonmacnois Clonard &c" persons of aspiring genius bent on improving themselves in theology would have been forced to repair from all parts of the island to Armagh to prosecute their studies there. It was a sufficiently high compliment to its school or university to grant it the exclusive privilege of approving of and authorizing persons to become public teachers. The decree understood in this manner was a very wise one inasmuch as it served to uphold uniformity of doctrine.
(57) Life &c. cap. 25
(58) Tr. Th. p. 632