This great work was carried out by twelve of his principal disciples, who filled the land with monasteries, and, as leaders of the new monastic church, became known as the twelve apostles of Ireland. In the Martyrology of Donegal Finnian is well described as ‘a doctor of wisdom and a tutor of the saints of Ireland in his time; for he it was that had three thousand saints at one school at _Cluain Eraird_, as is evident in his life; and it was out of them the twelve apostles of Erin were chosen;’ and it is added, ‘A very ancient vellum-book, in which are contained the Martyrology of Maelruain of Tamhlacht, and the list of the saints of the same name, states that Finnian was in his habits and life like unto Paul the apostle.’[103] Of these twelve apostles the earliest were the two Ciarans—Ciaran who founded the monastery of Saighir in Munster, and Ciaran, called _Mac-an-tsaor_, or ‘the son of the artificer,’ who founded, in 548, the more celebrated monastery of Clonmacnois in King’s County; Columba, son of Crimthan, a native of Leinster, who founded that of Tirrdaglas in the same year; Mobhi Clairenach, who founded the monastery of Glais-Naoidhen in Fingall; and Ninnidh, whose monastery was in an island in Lough Erne called Inismacsaint. Somewhat later were Brendan of Birr; the other Brendan, who became celebrated for his seven years’ voyage in search of the land of promise, and founded the monastery of Clonfert, where, like his master Finnian, he ruled as presbyter-abbot over three thousand monks; and Laisren or Molaisse of Devenish. Still later were Ruadhan of Lothra, Senell of Cluaininnis and Cainnech of Achabo, who lived till the end of the century. Of these, Brendan of Birr and Cainnech of Achabo were, like their master, of Pictish descent. [Sidenote: Saint Columba, one of the twelve.]